This study calculated the functional load of Chinese tones in different contexts by using an extensive corpus and the Markov model-based “Hockett-Wang algorithm”. The results show that, compared to vowels and consonants, tones carry the smallest functional load. In tones that are associated with monosyllabic, bi-syllabic, and multi-syllabic words, the functional load is inversely related to the number of syllables in that word. In other words, the more syllables in a word, the further the functional load of tones tends to decrease. Importantly, this study reveals a close correlation between the functional load of Chinese tones and the evolution of these tones. This is evidenced by the perceived imbalance of the functional load of different tonal contrasts within contemporary Chinese, as well as by the simulation results of the drastically declining functional load of Chinese tones in diachronic. These results may suggest that the declining load of Chinese tones is indeed the underlying driver for the merger and the resulting decline in the number of Chinese tones. The conclusions of the paper may shed new light for future research in the fields of phonology, speech engineering, as well as second language teaching.