The invention discloses a zoom system and a cam curve producing method of the zoom system. The cam curve producing method comprises the steps that the focal length and structure of a front fixed lens set, the focal length and structure of a zoom lens set, the focal length and structure of a compensating lens set and the focal length and structure of a rear fixed lens set are determined according to the technical index requirements of the zoom system; when the zoom system have different focal lengths, the distance L1 between the focal point of the front fixed lens set and the focal point of the zoom lens set, the distance L2 between the focal point of the zoom lens set and the focal point of the compensating lens set and the distance L3 between the focal point of the compensating lens set and the focal point of the rear fixed lens set are determined; a cam curve is obtained according to the multiple sets of L1, L2 and L3. The required zoom ratio and structural miniaturization are realized through the lens sets with the minimum movement distance, and the cam curve is easy to process.