The "supporting function method" is applied to floating orthogonal flat pushrod-disc cam combined mechanisms.The radius computational formula of curvature and " movement fidelity conditions" of the cam mechanisms
which meet the premise of the classⅠsynthesis problem-preset the conditions of cam axis O1(xO1
yO1)are studied and solved.An important theoretical foundation for solve the classⅠsynthesis problem is provided.At the same time
the "Supporting function method" is extended to a generic method to apply the disc cam combination mechanisms with floating orthogonal flat push rod.