Rubber particles are important components in latex, and have important effects on latex stability, rubber biosynthesis and processing properties. However, the difference of rubber particle size and distribution among different germplasms and the annual changes have not been systematically studied. In this study, 486 wild and cultivated Hevea germplasm planted in National Rubber Germplasm Respository were selected, and the latex were collected monthly during the tapping period from 2020 to 2021. The average diameter (Da), intermediate diameter (Di), intermediate diameter/average diameter (Di/Da), particle size≤0.259 μm frequency and particle size≤0.197 μm frequency of rubber particles were analyzed and studied. Da varied from 0.313 μm to 0.439 μm, and the coefficient of variation (CV) was 0.008-0.206. Di varied 0.209-0.366 μm, and the CV was 0.009-0.235. Di/Da varied 58.3%-84.9%, and the CV was 0.015-0.123. particle size≤0.259 μm frequency varied 31.1%-61.8%, and the CV was 0.013-0.322; particle size≤0.197 μm frequency varied 17.6%-46.4%, and the CV was 0.018-0.588. The five indexes showed significant differences among germplasm, which were suitable to be latex characteristic index. The correlation analysis of the five indexes showed that the correlation coefficient of Di and Da was 0.781; The correlation coefficient of particle size≤0.259 μm frequency and particle size≤0.197 μm frequency was 0.976; The correlation between Di and Di/Da was higher than that of Da, and the correlation coefficient reached 0.814. Di was also more correlated with particle size≤0.259 μm frequency and particle size≤0.197 μm frequency than Da, and the correlation coefficient reached 0.520 and 0.632, indicating that Di had a stronger statistical significance. Annual changes of Da, Di and Di/Da showed some difference. Da in June, July, August, October and December was not significant, and September and November were lower than other months. Di was not significantly different in June, July, August, September, November and December, and just a little lower in October. Di/Da had no significant difference in June, August and September, increased in November and December, but declined obviously in July and October. Da, Di, Di/Da, ≤0.259 μm frequency, ≤0.197 μm frequency in each month were all significantly correlated with the annual average. However, correlation coefficient were higher between alternate monthly measurements (June, August, October; July, September, November; August, October, December) and the annual average, reaching more than 0.850. That can be used for future rubber particle size testing.