针对高超音速化学非平衡流提出了两种隐式格式．一种是近似因子分解算法对角化形式在隐式ＴＶＤ（全变差递减）格式上的推广，另一种可视为隐式ＴＶＤ格式的ＬＵ分解形式．数值试验表明，本文给出的算法保持了ＴＶＤ格式的高分辨率特性，同时计算量大大减少，是高超音速化学非平衡流数值模拟的有效方法 Two implicit formats are proposed for hypersonic chemical non-equilibrium flow. One is the extension of the approximation factorization algorithm to the implicit TVD (Total Variation Decreasing) format and the other can be considered as the LU decomposition form of the implicit TVD format. Numerical experiments show that the proposed algorithm preserves the high resolution of the TVD format and greatly reduces the computational cost. It is an effective method for the numerical simulation of hypersonic chemical non-equilibrium flow