The progress in grey system research from 2004 to 2014 is summarized. Some important new conceptions, new models and new methods are presented, such as algorithm rules of grey numbers based on the “Kernel” and the degree of greyness of grey numbers, the concept of general grey number, the synthesis axiom of degree of greyness of grey numbers and their operations; the general form of buffer operator of grey sequence operator; four basic models of GM(1,1), namely the even grey model(EGM), the original difference grey model(ODGM), the even difference grey model(EDGM), the discrete grey model(DGM) , and their suitable type of each basic model; the similarity degree of grey incidence, the closeness degree of grey incidence and the three-dimensional absolute degree of grey incidence; the grey cluster model based on center-point and end-point mixed triangular whitenization weight functions; the multi-attribute intelligent grey target decision model, the two-stage decision model with grey synthetic measure of grey decision model, the grey game model, and the grey input-output model; the problems of robust stability for grey stochastic time-delay systems of neutral type, distributed-delay type and neutral distributed-delay type of grey control, etc. Moreover, the problems which remain for further studying and solving are proposed.