The invention discloses a front leg mechanism of a composite wheel leg type wheelchair. The front leg mechanism of the composite wheel leg type wheelchair is characterized by mainly comprising a rear connecting plate position and posture adjusting mechanism, a front connecting plate position and posture adjusting mechanism, a power transmission mechanism, a variable transmission mechanism and a control system. The rear connecting plate position and posture adjusting mechanism comprises a box, a rear connecting plate, a spindle, a crank, a guide rod, a sliding block, a guide rod seat, a left screw, a left rack nut, an upper electromagnetic clutch, a left handle, a rear guide wheel, a front guide wheel and a lower shaft. The front connecting plate position and posture adjusting mechanism comprises a front connecting plate, a right screw, a right rack nut, a lower electromagnetic clutch, a right handle and an upper shaft. The power transmission mechanism mainly comprises a spindle, a middle small shaft, a lower small shaft, a front guide wheel, a rear guide wheel, a middle bottom wheel gear and an underneath bottom wheel gear. The variable transmission mechanism mainly comprises a nut, a spring, a middle bottom wheel gear, a friction plate, a rear guide wheel and an upper shaft. The control system mainly comprises a sensing detection module, a driving module and a timing module.