A novel opener for opening cotton slivers comprises a shell, a feeding baffle plate, supporting legs, a conveying roller, a conveying belt, a conveying motor, a fixing rod, a primary loosening roller,a primary loosening roller belt pulley, a secondary loosening roller, a secondary loosening roller belt pulley, a primary garnetting roller, a primary garnetting roller gear, a primary garnetting roller belt pulley, a secondary garnetting roller, a secondary garnetting roller gear, a secondary garnetting roller belt pulley, a stripping roller, a stripping roller gear, a slackening motor, a primary garnetting motor, a secondary garnetting motor, a garnetting motor belt, a primary garnetting motor belt and a secondary garnetting motor belt. A first slackening cavity, a second slackening cavity,a first garnetting cavity and a second garnetting cavity are sequentially formed in the shell from one end to the other end. Raw materials can be sequentially slackened and garnetted, coarse treatment, fine treatment and stage treatment processes are performed in the opening process of the raw materials, and a system is strong in running continuity, stable in running and good in opening effect.