Objective To resolve the tough problem of how to observe the growing cells in an opaque vector. Methods The urethral epithelial cells from a young male New Zealand rabbit were inoculated, and were primarily cultured in vitro and subcultured for 3 passages. Then, the urethralepithelial cells were cultured in the collagen chitosan complex for 3, 7, 14 and 21 days. The cells were dyed with 6-carboxyfluorescein diacetateacetoxymethyl ester and propidium iodine, respectively. Then, Interactive Laser Cytometer was used to detect the growing cells. Results The urethral epithelial cells grew and proliferated very well in the collagen chitosan complex vector. After the urethral epithelial cells grew in the collagen-chitosan complex vector for 3 and 7 days, the fluorescent density amount of the surviving cells were(1.09±0.13)×10.8 and (2.04±0.13)×10.8, respectively. However, after 14and 21 days, the fluorescent density amount of the surviving cells was (0.55± 0.09)×10.8 and (0.47±0.03)×108, respectively. There was a significant difference when compared with the amount of the surviving cells at 3 and 7 days（P＜0.05）.Conclusion Using Interactive Laser Cytometer for measurement of the green and red fluorescent densities of different waves, the activity of the cultured urethral epithelial cells in vitro can be rapidlymeasured with the in situ quantitation method. This method solves a difficult problem of observing the growing cells in an opaque vector. The dynamic growing state of the engineering tissues can be observed.