In order to meet the alignment requirements of the primary and secondary mirrors of the Chinese giant solar telescope (CGST), an active alignment method of laser truss based on laser interferometry is proposed. First, the optical structure and measurement principle of the CGST laser truss measurement system are introduced, then the laser truss kinematics model and active alignment optical model are established, and the error propagation characteristics of the system are discussed. Then, the effects of temperature field and local atmospheric turbulence on the active alignment method are discussed through the atmospheric optical model. The results of motion analysis and optical modeling show that in the visible band, when the ranging error of the laser truss is less than 5 μm and the environmental temperature gradient is less than 0.381 K/m, the wavefront root-mean-square caused by alignment error is better than λ/10. In addition, under the conditions of Kolmogorov turbulence and typical daytime near-surface turbulence, atmospheric turbulence does not seriously reduce the sensitivity of laser truss measurement. It can be seen that the proposed method can meet the requirements of active alignment of CGST secondary mirror.