In this study, the flexural behaviors of a composite plate jointed with I profile jointing element have been carried out experimentally and numerically. As a load type, four point flexural tests have been used in order to study performances of jointed composite plates under bending load. The effects of jointing geometry parameters ratio of the width of lock to width of semi-specimen (b/W), lock middle/end width to the width of lock (z/b) and the length of lock to the width of semi-specimen (h/2W) have been investigated. According to the investigation optimum jointing parameters have been found with the h/2w ratio of 0.5, b/w ratio of 0.5 and z/b ratio of 0.5. Abaqus 6.11 finite element program has been used in order to support the results obtained from the experiments. Damages mostly have been seen on jointing lock elements.