The MRTR method has been recognized as an effective iterative method for singular systems of linear equations. The MRTR method is based oil the three-term recurrence formula of the CG method and the algorithm is proven to be mathematically equivalent to the CR method. This paper will describe the algorithm of the cs_MRTR method for solving complex symmetric linear systems, and prove that this method is mathematically equivalent to the COCR method. Numerical experiments indicate that the cs_MRTR method convergences more stably compared with the COCR method.