A series of experiments on the relationship between pressure and flow rate in the cooling pipe network of injection mold were carried out to verify the applicability of the analysis method of traditional pipe network in the mold design.The test result showed that the current method based on the Darcy-Weisbach equation was not correct.Neither MPI，the major CAE software for injection molding，nor some CAE software developed in China gave correct result.Although the Darcy-Weisbach equation still has certain use for reference，its basic theory on resistance calculation is not applicable to the cooling analysis of the injection mold.The reason was discussed and the correct analysis method was proposed.