In　order　to　make　the　gait　of　a　bipedal　robot　more　human-like　and　to　further　improve　the　efficiency　of　energy　utilisation,　this　paper　combines　preview　control　strategy　and　a　knee　extension　strategy　to　design　a　bipedal　robot　gait　planning　method　based　on　a　variable　centre-of-mass　height　hybrid　strategy.　The　core　idea　is　to　achieve　gait　stability　and　coordination　by　controlling　the　robot＇s　centre-of-mass　height.　Firstly,　the　horizontal　centre-of-mass　trajectory　of　the　biped　robot　is　generated　based　on　Preview　Control　strategy　with　a　constant　centre-of-mass　height;　secondly,　the　vertical　centre-of-mass　trajectory　is　generated　based　on　the　knee　joint　extension　strategy　by　trajectory　planning　of　the　robot＇s　knee　joint;　finally,　the　horizontal　and　vertical　centre-of-mass　trajectories　and　foot　point　positions　are　combined　by　the　inverse　kinematics　of　the　bipedal　robot　to　plan　the　offline　gait　of　the　bipedal　robot　with　variable　centre-of-mass　height.　The　experimental　results　show　that　the　bipedal　robot　is　able　to　walk　smoothly　with　the　planned　gait,　with　better　human-like　characteristics,　and　requires　less　knee　torque　than　bent　knee　walking　mode　with　a　constant　centre　of　mass　height,　which　improves　energy　efficiency.　©　2023　IEEE.