[Objectives] The black Amur bream (Megalobrama terminalis) is an indigenous fish species, which has been identified to hold an important position in fishery production in the lower reaches of the Pearl River. This study aims to investigate the inter-annual variation on body length-weight relationship, Fulton’s condition factors (K) and age structure of M. terminalis population in the course of 2010-2018 in the downstream of Pearl River. [Methods] From 2010 to 2018, 1 785 specimens of M. terminalis were collected. Body mass and body length of all the samples were measured. In this study, we investigated the growth pattern of M. terminalis, basing on the body length, weight and age structure of M. terminalis. The power function of the body length and body weight relation equation: W = aLb was used to compare the variation trend of M. terminalis from 2010 to 2018. SPSS software (version 19.0) was used for data processing. We examined significant differences between allometric growth parameters b and 3 by t test. Descriptive statistics was presented as mean ± standard deviation (Mean ± SD). [Results] The results indicated that there was a decreasing trend in body length and proportion of individuals over 5+ years of M. terminalis population in Zhaoqing section of the Lower Pearl River from 2010 to 2018. Meanwhile, the body length-weight power function correlation condition factors (a) ranged from 0.011 to 0.004, and the value of allometric factor (b) ranged from 2.816 to 3.261 in the present study. M. terminalis population showed negative allometric growth in 2010, 2011 and 2014, while positive allometric growth in 2013, 2015-2018. The fatness of M. terminalis population presented a gradually increasing trend during 2010 to 2018. In addition, the proportion of daily average water temperature above 20 ℃ in ZhaoQing section of the Pearl River gradually increase, while the number of flood peaks decreased significantly and the distibution of flood peaks turned into intensively. Moreover, there was a positive relationship between allometric factor and water temperature and discharge, verifying the relevance between fish growth and habitat environment. [Conclusion] In general, high fishing pressure might be responsible to accelerate growth rate of M. terminalis population in the downstream of the Pearl River, causing negative allometric growth of M. terminalis population. Furthermore, implement of the fishery ban management and variation of water temperature in the lower reaches of the Pearl River might lead to the ascent in fatness of M. terminalis population.