The high proportion of grid-connected photovoltaics (PVs) leads to a dramatical increase of supraharmonic emissions at distribution network. The influence of supraharmonic interaction between grid-connected PVs and distribution network is much more remarkable than that in single PV grid-connected system. So the high proportion of grid-connected PVs reduces the stability of the grid. In order to reveal the characteristics of supraharmonic emission at high proportion of PVs grid-connected, the effect of PVs connecting to grid on supraharmonic emission is discussed. Firstly, the propagation of supraharmonic current at high proportion of grid-connected PV is described. Considering background harmonic emission of grid and control circuits of PVs, a mathematic model is built to calculate the value of supraharmonic currents and summarize the law of supraharmonic propagation at high proportion of grid-connected PVs. On the basis of the model built by PSCAD simulation platform, the supraharmonic emission from individual PVs is obtained. The model is also used to show the influence of backgrounds and PVs on supraharmonic emission. The last but not the least, the model is verified, based on measured date of concentrated PV access in Quanzhou city, Fujian Province.