Abstract: In order to investigate the rule of pulpy growth and the influence of cell size and morphology on pulpy development, two kinds of bitter gourd with different pulp thickness(LX1-3 and ZK54) were used to analyze the dynamic changes of pulpy thickness and the parameters of cell size and morphology in different periods, and to study the correlation between different indexes. The results show that: (1) Pulp thickness increased as the fruit develops, andsignificantly different between two germplasms at 17 and 23 days after flowering. (2) Cell area of LX1-3 was significantly different at 10,17and 23 days after flowering, andcell perimeter, length and width were significantly different at all 4 sampling times. Cell area ofZK54was significantly larger at 17 days after flowering than at 10 days after flowering, cell perimeter and length were significantly different at 3, 10 and 17 days after flowering, cell width was significantly different at all 4 sampling times. Cell area, perimeter, length and width of LX1-3 at 17 and 23 days after floweringwere significantly greater than ZK54. (3) Cell aspect ratio and roundness of LX1-3 at 17 and 23 days after flowering were significantly greater than at 3 and 10 days after flowering. Cell aspect ratio and roundness of ZK54 were significantly higher at 17days after flowering than at 3 and 10 days after flowering, but these indicators at 23 days after flowering were rather smaller than at 17 days after flowering. Cell aspect ratio and roundness of LX1-3 were significantly higher than ZK54 at 17 and 23 days after flowering. (4) Correlation analysis showed that cell size and morphological parameters were significantly or extremely significantly positively correlated with flesh thickness, indicating that cell development played a key role in the growth of bitter melon fruit.