Translations of the Ave Maria (Hail Mary) made before the May Fourth Movement were into Classical Chinese for the practical reason that many of the words in colloquial Chinese had, before then, no written form; and for the cultural reason that no religious text of any significance would be written in the vernacular tongue. Certainly, in pre-May Fourth China, even personal letters between private individuals were written in Classical Chinese (possibly via profession letter writers).

The earliest translation I am aware of is a clumsy affair derived from Latin:

Ave Maria
亞物瑪利亞
yàwù Mǎlìyà
Hail Mary

gratia plena
滿被額辣濟亞者
mǎn bèi gélàjìyà zhě
full of grace

Dominus tecum
主與爾偕焉
Zhǔ yǔ ěr xié yān
the Lord is with you

Benedicta tu in mulieribus
女中爾為讚美
Nǚ zhōng ěr wéi zhànměi
Blessed art thou amongst women

et benedictus fructus ventris tui Jesus
爾胎子耶穌併為讚美
ěr táizǐ Yēsù bìng wéi zànměi
and blessed is the fruit of thy womb Jesus

Sancta Maria mater Dei
天主聖母瑪利亞
Tiānzhǔ shèngmǔ Mǎlìyà

ora pro nobis peccatoribus nunc et in hora mortis nostrae
為我等罪人今祈天主及我等死候
wèi wǒděng zuìrén jīn qí Tiānzhǔ jí wǒděng sǐhòu
Pray for us sinners now and at the hour of our death

Amen
亞孟
yàmèng
Amen

The translator obviously had difficulty translating certain concepts into Chinese. There is no attempt to translate some words and these are merely transliterated by strings of nonsense characters: these words are ave 亞物 (hail) and gratia 額辣濟亞 (grace). Benedicta 'blessed' is translated by 讚美 which really means 'praised'; my feeling is that 見福 jiànfú or 受福 shòufú ('to have received good fortune') better retains the sense of the original. The word is also used to translate hora 'hour', although it more usually means 'to wait'—the usual translation would be shí.

A slightly later translation exists that addresses some of these issues. It is identical to the older translation, except that ave is translated as 申爾福 shēn'ěr fú (literally, 'Wish you good fortune'), and gratia as 聖寵 shèngchǒng. In my opinion, the choice of is not appropriate, as it implies the indulgent love of a parent to his child; I think the word ēn, which is the favour and grace of a ruler towards his subject, more accurately encapsulates the meaning of the Latin gratia.

A still later Classical Chinese version exists, which, again, is essentially the same, aside from 萬福 wànfú being used to translate ave. This version is still in current use.

When older Chinese Catholics pray the rosary, they do so in a manner that is almost identical to the recital of Buddhist sutras: a rhythmical, sing-song, Buddhist chants:chanting sort of prayer that sounds alien to Christian ears. As the text is entirely in Classical Chinese, most Chinese may not actually understand the words, but merely memorise the sounds. For this reason, the version which is currently used in most Mandarin and Cantonese churches is a vernacular one, the older classical version being used only by non-Mandarin speakers, for whom the Mandarin vernacular is incomprehensible when read in their dialect.

萬福瑪利亞,
Wànfú Mǎlìyà
Hail Mary,

你充滿聖寵,
nǐ chōngmǎn shèngchǒng
full of grace,

主與你同在,
zhǔ yǔ nǐ tóngzài
the Lord is with you;

你在婦女中受讚頌,
nǐ zài fùnǚ zhōng shòu zànsòng
blessed are you among women,

你的親子耶穌同受讚頌。
nǐ de qīzǐ Yēsù tóngshòu zànsòng
and blessed is the fruit of your womb, Jesus.

天主聖母瑪利亞,
tiānzhǔ shèngmǔ Mǎlìyà
Holy Mary, Mother of God,

求你現在和在我們臨終時,為我們罪人祈求天主。
qiú nǐ xiànzái hé zà wǒmen línzhōngshí wèi wǒmen zuìrén qǐqiú Tiānzhǔ
pray for us sinners, now, and at the our of our death.

亞孟。
yàmèng
Amen.

References:
《祈禱手冊》香港公教真理學會:香港(1995)。
Ave Maria. Commissariat of the Holy Land, Franciscan Monastery. Washington, D.C. (1936).
Ave Maria in 404 Lingue. Ordine Equestre del S. Sepulcro di Gerusalemme. Milano (1931).
Many thanks to David Landsnes of Kendall Park, New Jersey, for providing some of the source material I cite.
A.M.D.G.