Based on data from 45 soil cores, 35 lake sediment cores, and 32 sea sediment cores in China, this study found a type of ^239+240Pu peakless distribution cores in soil, lakes, and marine environments, and discussed their causes of ^239+240Pu peakless distribution. The results show that there were two main types of peakless distribution of ^239+240Pu in soil core samples: one that the ^239+240Pu specific activity increased with depth, and the other that the ^239+240Pu specific activity decreased with depth; when using a Convection Dispersion Equation (CDE) model to simulate the migration behavior of ^239+240Pu in soil cores, the apparent convection rate showed a positive correlation with the ^239+240Pu maximum depth (n=45, R²=0.847). There was only one type of peakless distribution of ^239+240Pu in lake and ocean core samples: the ^239+240Pu specific activity decreased with depth. Meanwhile, the sedimentation rate of lake core samples (n=35, R²=0.921) or the maximum apparent convection rate of marine core samples (n=32,R²=0.949) also showed a positive correlation with the ^239+240Pu maximum depth. The maximum apparent convection rate of the exchangeable ^239+240Pu in the peakless distribution core sample was close to the sedimentation rate, and the maximum apparent convection rate didn’t affect the vertical distribution of ^239+240Pu in the core sample.