The purpose of this study was to provide high frequency word lists for Mandarin-speaking children between 3 and 6 years of age and to explore the differences between each part of speech (POS) category among different age groups. Participants were 209 typically developing native Mandarin speakers aged between 3 and 6 years, born in Taiwan, and recruited from Mandarin-language preschools in Taipei, New Taipei City, and Miaoli. Language samples were collected through conversations, free play, and story retelling. The researchers then transcribed the samples, segment utterances, and words, tagging the POS corresponding to each word. The frequencies of word occurrences were then analyzed and ranked to generate a high frequency word list. The mean frequency of each POS category was calculated to identify significant differences between age groups. The results showed high frequency word lists, including the corresponding POS tagging. Significant differences were found in 10 of the 11 POS categories among age groups. The results of this study presented preliminary information concerning high frequency words produced by Mandarin-speaking children aged between 3 and 6 years and the development of their use of each POS category.