Based on the three-dimensional radar mosaic data from April to June in 2016-2019 and the differences in triggering conditions, a classification for warm-sector squall lines with vastly different formation mechanisms during the pre-flood season was proposed. They were divided into two types: squall lines that developed in the warm sector after frontal triggering(Type I warm-sector squall lines), and squall lines that were generated and developed in the warm sector(Type II warm-sector squall lines). On this basis, the distributions of short-term heavy rainfall and thunderstorm winds were compared in terms of large-scale environmental conditions and mesoscale radar echo characteristics during the occurrence of squall lines. The results showed that: Type I warm-sector squall lines were mostly formed in plain areas, while Type II warm-sector squall lines were mostly generated on the windward slopes of mountains and coastlines. Both squall lines were accompanied by obvious short-term heavy precipitation, which was easy to cause rainstorm and flood; Type I warm-sector squall lines were prone to producing regional thunderstorm winds, while Type II warm zone squall lines produce scattered thunderstorm winds. The Type I warm-sector squall lines had longer lifecycle, more vigorous convective development, and a faster moving speed, while the Type II warm-sector squall lines had shorter lifecycle and a slower moving speed with weaker echo intensity. Both types of squall lines had good water vapor conditions and vertical shear conditions of low-level winds at 0-3.km, and the dynamic and thermal conditions are better when Type I warm zone squall lines occurred.