An algorithm for constructing valid cuts is presented for the new decoding model at the base of elementary transformation on the parity check matrix. Valid cuts at current fractional solution can be obtained directly by this algorithm and therefore the efficiency will be enhanced. 针对该模型,给出一个基于校验矩阵初等变换处理的有效割(奇偶校验割)构造算法,可直接获得当前分数解的有效割,提高了有效割寻找效率。