Abstract: Systematic laboratory research methods of acidiza-tion stimulation in under-injected wells with low permeability are introduced in this paper. Acidization and unplugging operation can be carried out pertinently in under-injected wells with low permeability through reservoir evaluation before acidization operation, reservoir sensitivity study, long and short core flow modeling experiment in combination with FNMR residual acidization testing, selection of technological parameters of acidization and evaluation after field operation. Application of these methods in oilfields have achieved good results.