The invention discloses an epoxy resin curing agent and a modification method thereof. The epoxy resin curing agent consists of the following components in parts by weight: 35-50 parts of menthane diamine, 10-20 parts of epoxy compound and 40-45 parts of ethylene glycol butyl ether, wherein the epoxy compound is a compound containing one or two glycidyl ether groups. The epoxy compound and excessive menthane diamine have an addition reaction to obtain an addition product of menthane diamine, so that the toxicity of the curing agent is reduced, the compatibility with an epoxy resin is improved, the anti-whitening performance of a product is improved, the curing agent of the epoxy resin is good in use security, and the quality and the quality stability of the cured epoxy resin are improved.