Spectroscopic properties of Ho3+-doped ZnCl2-based glasses are investigated. The Ω2 value of the glass is especially large compared with those in fluoride glasses while the Ω4 and Ω6 parameters are relatively small. Decay measurements for three excited states F55, S25+F45, and F2,35+K83 were performed and multiphonon relaxation (MPR) rates of the respective states were estimated. The experimental data are approximately on a line expressed by WMPR=C exp(−αΔE) with C=5.0×107 s−1 and α=4.0×10−3 cm. The host-dependent constant C is very small, contributing to high quantum efficiencies of emissions. The Ho3+ concentration dependence of the fluorescence lifetime of the F55 and S25+F45 levels was also investigated. The concentration quenching of the S25+F45 level can be explained by the cross-relaxation mechanism: S25→I45 and I75←I85 transitions.