The invention belongs to the technology field of biomass processing, and provides an environmentally friendly biomass burning system. The system comprises a smashing assembly, a burning assembly, an off-gas burning assembly, and a waste heat utilization assembly. Wherein, the smashing assembly comprises a feeding trough, a conveying box, a conveyor belt, and a smashing device; the feeding trough is mounted on the left end of the conveying box; the conveyor belt is mounted on a lower end of the inside of the conveying box; the smashing device is mounted on the right end of the conveying box. The biomass can be conveyed into a burning cavity by mounting the conveyor belt; the biomass can be smashed by the smashing device, which is beneficial to the full burning of the biomass; the heat of burning can heat the water in a boiler; The off-gas discharged into the off-gas burning cavity can be further burned by an oxygen generator and a burner to prevent the generation of harmful gases due toinsufficient burning; the treated off-gas heats the water in a water tank through a heat transfer pipeline, and finally the off-gas is discharged after dust removal by a bag filter.