To study the calibration accuracy of stuctured light system based on cross-ratio invariant,measuring error and light-plane calibration error of system are analyzed,and an error propagation model is established by employing theories of error and matrix disturbance. According to the error propagation model,the precision demands of calibration parameters and samples under a special condition in measuring distance of 1 000 mm and measuring accuracy of ±0.5 mm is presented. The error propagation model is validated through experiments,experimental results show that proposed model can provide theory basis for improving measuring accuracy of structured light system.