Abstract: The virulence-attenuated salmonella containing the pGMCSF-SS plasmid was introduced in this experiment, which had been cultured for 13h ,in this time, the samples were got in the interval of 1h .After that, the OD600 was detected using UV Spectrophotometer,at the same time, the number of the live salmonella was received by plate count .According to these data, an mathematical model of linear regression was founded between the bacterial logarithm and bacterial turbidity, which was Y=1.5568x+7.0944 R2=0.9543. The correlativity had a significant difference︱r︱>r0.01. For further validating the stability of the equation, in the culturing time, the samples were obtained in random. By comparing Y obtained from the equation and plate count, there was no significant difference (p>0.05). The regressive model not only overcome the disadvantage of traditional counting method, but also be convenient to use.