A differential measurement configuration with single cylindrical focusing lens for thermal lens technique is proposed and a theoretical model based on the optical phase shift theory and the ABCD rule for Gaussian beam propagation is developed to describe the thermal lens amplitude. The optimal configuration condition and the theoretical limit of measurement sensitivity are derived. The theoretical results show that this measurement configuration can obtain the same measurement sensitivity as the measurement configuration with double cylindrical focusing lens. The influences of configuration parameters on the light intensity distribution on the detection plane and the thermal lens amplitude are analyzed by the theoretical model, as well as by the finite element method. The both reach a good agreement, which proves the validity of differential measurement configuration with single cylindrical focusing lens and the correctness of the theoretical model.