A simulation model of development stages of greenhouse cucumber(Cucumis sativus) was developed based on photo-thermal reactions of crop development rate.The concept of physiological development time(P_DT) was used as the scale to measure the greenhouse cucumber development stages.Experimental data of different varieties were used to validate the model.The results show that the PDT value for the duration from sowing date to the first harvest date was 30 days,with 3,11,9,5,2 days,respectively,for the duration from sowing to germination,germination to tendril elongation,tendril elongation to flowering,flowering to fruit setting,and fruit setting to first harvest.The root mean squared error(R_MSE) between the simulated and observed results for duration of germination,five leaf stage,tendril elongation,flowering,fruit setting,and from sowing to first harvest,respectively,was 0,2.6,1.7,0.8,2.1,1.4 days,which was lower than the prediction errors using the growing degree days(GDD)(0.7,10.0,5.7,2.4,2.5,22.0 days,respectively).