With integral structure, good thermal insulation property (warm keeping or cold insulation), compact structure and small volume, BAOYI steam jacket plug valve is especially applicable to the pipelines for petroleum, chemical product, metallurgy, pharmacy, etc., namely the easily-solidified and high-viscosity medium, and the design pressure of the jacket thereof can maximally reach up to 4.0MPa. Additionally, this product can effectively reduce medium heat loss and prevent medium crystallization, solidification, etc.