Learning through repetition is a fundamental form and also an effective method of language learning critical for achieving proficient and automatic language use. Massive repetition priming as a common research paradigm taps into the dynamic processes involved in repetition learning. Research with this paradigm has so far used only emotionally neutral materials and ignored emotional factors, which seems inappropriate given the well-documented impact of emotion on cognitive processing. The present study used massive repetition priming to investigate whether the emotional valence of learning materials affects implicit language learning. Participants read a list of Chinese words and made speeded perceptual judgments about the spatial configuration of the two characters in a word. Each word was repeated 15 times in the whole learning session. There were three types of words, negative, positive, or neutral in their emotional valence, presented in separate blocks. Although similar levels of asymptotic performance were reached for different valence conditions showing comparable total effects of learning, learning of the positive words was found to be associated with fewer plateaus of shorter durations and to reach saturation earlier, compared with neutral and negative words. The results showed for the first time that the emotional valence of learning materials has significant effects on the time course of learning so that positive materials are learned faster and more efficiently, relative to negative and neutral materials. The study indicates the importance to explicitly consider the role of emotional factors in implicit language learning research.