Aiming at the characteristics of high precision requirement and difficult sampling in the working state of dual-arm cooperative robot，a reliability analysis model of dual-arm cooperative robot was proposed based on quadratic fourth-order moment estimation method for the analysis of robot position error.The system was transformed into a series system by using extreme value distribution principle,and each order moment of limit state function was obtained by using each order moment of random variables.The probability density function of limit state function was determined by the best square approximation method,so that the reliability of single manipulator can be solved.The system reliability method was used to solve the reliability of the dual-arm cooperative robot.Finally,taking the 6-DOF dual-arm cooperative robot as an example,the effectiveness of this method is verified by comparing with Monte Carlo simulation.