For solving the problem of secondary lens occlusion in Cassegrain solar condenser， a lens correction method was proposed to reduce the obscuration ratio. On the basis of the traditional concentration ratio and obscuration ratio formula， the correction formulas were proposed. A Cassegrain condenser was analyzed with Zemax software， the concentration ratio was 280， and the obscuration ratio was 0.33.The results showed that using lens correction method， the obscuration ratio of the designed Cassegrain condenser was reduced by 36.36%， the concentration ratio of the condenser was improved， and the spot distribution on the receiver surface was more uniform.