The invention discloses a construction technology of a soundproof inner wall. According to key points of the technical scheme, the construction technology includes the following steps that S1 removalis performed, specifically, a painting layer on the inner surface of an original wall is completely removed, and then an interface agent is painted on the wall surface; S2 repair is performed, specifically, then white glue is pasted to cracks of the inner wall surface, then gridding cloth is laid on the entire inner wall surface, and cement mortar is painted until the wall surface is flat; S3 painting is performed, specifically, first a layer of base putty is painted, then two layers of surface putty are painted, after polishing, a layer of alkali-resistant primer is painted, then three layersof soundproof coat are painted, a soundproof coating is formed, and finally two layers of latex finishing coat are painted; and the soundproof coating is prepared from the following components in parts by weight: 35 to 40 parts of water-borne epoxy resin emulsion, 15 to 20 parts of a curing agent, 40 to 45 parts of rubber modified nano inorganic filler, 5 to 8 parts of compatibilizer, 3 to 5 parts of montmorillonite, 5 to 8 parts of mica powder, 0.15 to 0.3 part of a leveling agent, 0.3 to 0.5 part of dispersant, 0.1 to 0.2 part of defoamer, and 15 to 20 parts of water. The construction technology has the following advantages that the soundproof coating is good in soundproof effect and good in toughness.