Abstract: Based on English-Chinese diachronic parallel corpora, this paper examines explicitation and implicitation of the neuter pronoun "it" from both formal and semantic perspectives.The aim of the study is to investigate the source language shining-through effect by drawing on the framework of semantic transparency and signal simplicity.Shifts of explicitation and implicitation are divided into three levels:lowest, medium and highest.The current findings demonstrate that:1) Source language shining-through effect has ascended, as evidenced by the increased occurrences equivalent to the English word "it" from the first to the third period; 2) The frequencies of the explicitation of "it" in translations have increased, with the co-reference ambiguity shrunk, as is shown by diachronic analysis of the translated texts; In comparison, the occurrences of implicitation has become lowered on the whole; 3) The frequencies of the Chinese word 它 "ta" are the highest when co-occurring with material verbs, and decrease with the mental, relational and verbal classes in turn.From a diachronic perspective, the frequencies of "ta" collocating with material and mental verbs have increased gradually over the three periods.It is thus proved that the semantic collocation of "it" in the original English texts has an effect on the occurrences of the corresponding "ta" in the translated texts across time.The mechanism operating behind the change of source language shining-through effect has also been investigated.