The invention discloses a joint estimation method for SOH (state of health) of a lithium ion battery. Internal resistance and capacity of the battery and various external characterization quantities of a discharge curve are obtained with specific testing methods respectively, and the current SOH of the battery is judged jointly by integrating the characterization quantities. The joint estimation method for the SOH is provided on the basis of a large number of experiments and summaries in order to solve the problems that the conventional estimation method for the SOH of the battery consumes long time, has large error and the like, the SOH evaluation time can be shortened, limitations of the conventional single parameter based determination method can be avoided, the SOH estimation precision can be improved, and the joint estimation method can be popularized and applied to engineering practice and other types of batteries.