The low temperature permanent photoconductivity in PbTe/Pb_(0.88)Sn_(0.12)Te multi-quantum wells grown by molecular beam epitaxy was studied both theoretically and experimentally. The decay of the photoconductivity was analyzed in terms of tunneling-as- sisted electron-trap recombination. The theoretical result agrees with the experimental one. The band offsets of both the [111] valley and the others at PbTe/Pb_(0.88)Sn_(0.12)Te interfaces were estimated by fitting the calculated decay curve of the photoconductivity to the experi- ment data.