Modern Chinese Dictionary is an authoritative, standard literature dictionary that is normative, scientific, and practical. Examining the onomatopoeias in this dictionary in detail is very valuable. This paper examines 235 onomatopoeias included in the recently edited and published 6th edition and categorizes them by the subjects they represent and number of syllables. In addition, the method of expression, morphology and differences from the 5th edition are examined. Out of the 235 onomatopoeias, there are 61 with a written language indicator, 1 with a dialect indicator, and 173 without any indicator (used in spoken words). An analysis based on the number of syllables revealed 83 monosyllabic words(35.3%), 142 disyllabic words(68 AA type, 74 AB type)(60.4%), 1 trisyllabic word(ABB type, 0.4%), and 9 four-syllable words(4 AABB type, 4 A裏BC type, 1 ABCD type) (3.8%). The expressions used to describe the pronunciation of the onomatopoeias are simple, and they often include the words ‘describe’ and ‘sound.’ The meanings are explained so that readers can infer the sounds easily, and then one or two examples are presented. However, a large number of entries for the onomatopoeias used in written language do not have examples, making it hard to infer their pronunciation. As Modern Chinese Dictionary places great importance on normativity, it is very strict in handling homophonous onomatopoeias; therefore, one homophone is usually selected. A comparison with the 5th edition showed that seven new onomatopoeias were added and some onomatopoeias were given additional examples or more detailed descriptions of their meanings.