The invention provides a variable 
pitch radius based star chain transmission stepless speed change device. The device is characterized in that: a star 
sprocket device on a transmission main shaft is driven by adopting a motor, and forms a 
sprocket transmission pair by combining with a bush 
roller chain; the star 
sprocket device comprises a control wheel arranged on the transmission main shaft, and left and right auxiliary wheels which are arranged on two sides of the control wheel respectively; a control wheel 
stator and a control wheel rotor which are connected with the transmission main shaft are arranged on the inner 
diameter of the control wheel body; two rows of staggered supports are uniformly distributed on the circumference of the outer profile of the control wheel, and are connected with synchronizers on the left and right auxiliary wheels through connecting rods. According to the variable 
pitch based star chain transmission stepless speed change device, the problems that a conventional traditional friction type stepless gearbox can not complete power transfer without friction, a high-power stepless gearbox can not realize high push power adjustment without a hydraulic 
system, and a silent chain transmission stepless gearbox 
system has higher price and the like can be solved. The variable 
pitch radius based star chain transmission stepless speed change device is suitable for various heavy construction equipment under heavy-load low-speed conditions, such as middle-high class cars, 
machine tools, hoisting machinery, heavy-load vehicles, lorries, elevators, transmission machinery.