The designing thought of verification equations in PGHR protocol is singular，that is，a verification equation targets only one constraint，ignoring their joint effect． In this paper，a new ZK-SNARK protocol——— CPGHR protocol———was obtained by using the indivisible properties of additional constant coefficient factors and the combined effect of verification equations to achieve effective compression of the PGHR protocol． At the same time，a strict verification of the security of the new protocol was given，and the validity of the protocol was theoretically analyzed and experimentally verified． The results show that the amount of evidence of the new protocol is reduced by about 75% ，and the calculation efficiency is improved by about 33% ．