Through systematically analysing the dynamic strain aging behaviour and the testing data of structural steel DH-36, the constitutive model of the third-type dynamic strain aging has been developed. Then based on thermal-activated physical concept constitutive model and the combinatorial principle of plastic flow stress, a unified constitutive model is finally obtained with the description for the third-type dynamic strain aging. This model not only can describe the third-type dynamic strain aging phenomenon, but also the mechanical behaviour of DH-36 steel in a wide range of temperatures （77-1 000 K） and strain rates （0.001-3 000 s^-l）. There is a good agreement between theoretical predictions and experimental results.%通过对DH-36钢动态应变时效的规律和试验数据进行系统分析，发展和建立了描写第3种动态应变时效的本构模型．然后基于热激活物理概念本构模型和塑性流动应力组合原理，加入对第3种动态应变时效的描述，获得了统一本构模型．该模型不仅可以描写第3种动态应变时效，还可以预测DH-36钢在温度77K—1000K，应变率O．001s^-1—3000s^-1范围内的塑性流动应力，通过比较发现统一本构模型预测结果与试验结果吻合很好．
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