Two bio-insecticides, Bacillus thuringiensis (Bt) and Ectropis oblqua Nuclear Polyhedrosis Virus (EoNPV), are commonly used for control of pests as mixtures. The efficiency against pests has a complex relationship of dosage-time-mortality because of the bio-insecticides’ chronic lethal effect. However, evaluating ratios of two bio-insecticides had not been investigated. The present investigation studied dosage-time-mortality on the second instars larva of Ectropis oblqua using the theory and method of tupu analysis from Ye et al and fingerprint chromatogram analysis from Cao et al. Analysis of variance of multiple factors to bioassay data of Ectropis oblqua larva was conducted using the SPSS statistical analysis system and Excel drawing software. Multiple curves of the mortality process of the pest or the efficiency at intervals of time at different doses were established. One-way analysis of variance to the data from the curves was conducted by the SPSS statistical analysis system and similarity, and non-similarity were obtained according to tupu I, and Ⅱ, then similarity coefficient, and non-similarity coefficient were calculated respectively. Finally, an evaluation index of efficiency of mixed bio-insecticides to the pest was constructed based on two coefficients, i.e., the Q value. The result showed that Q values of four ratios of Bt∶EoNPV, 9∶1, 7∶3, 4∶1 and 2∶3, were 200,100,31.0 and 23.8, respectively, indicating that 9∶1 was the best ratio with the maximum Q value. The finding was consistent with previous bioassay. Reliability and application of the tupu analysis method were also discussed.