Abstract: It is assumed that the kinematic joints are ideal or perfect in the dynamics research of general multi-body system. However, the realistic joints include not only the clearance and friction but also contact-impact, local deformation and wear between the joint element arising from the clearance. On the one hand, the presence of clearance effect in joints causes the impact dynamic load, noise and high frequency vibration. On the other hand, the system accuracy, reliability and the service life of mechanism system will be affected due to the joint clearance. The research background of joint effects in multi-body system dynamics over the past several decades is carried on the detailed analysis. The modeling processes of joint effects that contain the kinematics model of clearance, contact force model and wear model are summarized. The advanced in joint wear effect of multi-body system dynamics is focused on specially, and the comparative analysis of two common wear model of Reye's hypothesis and Archard's wear model are carried out to illustrate their differences. The evolution form and main wear parameters consisted in the contact pressure, sliding distance and contact area of the Archard's wear model are specific developed. The modeling method of key parameter for contact pressure is analyzed specially, and it is explained that the difficulty of contact pressure is formulated by Winkler elastic foundation theory. Moreover, the kinematic models of four different style joints with clearance are briefly introduced respectively. The general modeling method of multi-body system dynamics considering joint irregular wear clearance is discussed in a flow chart way, and the planar five-bar mechanisms is taken as an example to account for modeling process of multi-body system with irregular wear clearance. Lastly, the future development trend and application prospect of joint effect model in the multi-body system dynamics are discussed respectively.