A mathematical model for image reconstruction of the oilair lubrication ECT system was established,and the main causes and influencing factors of morbidly were analyzed.The morbidly degree of the sensitivity matrix in the image reconstruction of oil-air lubrication ECT system was diagnosed employed the condition indexvariance decomposition ratio (CIVDP) method.The results show that there is a strong complex collinearity between the sensitivity matrix column vectors,that is,there is strong or even serious morbidly in the image reconstruction of oilair lubrication ECT system.Oil film thickness as well as number of plates affect the morbidly of image reconstruction.Through the regression analysis and residual processing of the sensitivity matrix column vectors,the degree of morbidly is effectively weakened.