Let K r+1 be the complete graph on r+1 vertices. A graphic sequence π =(d_1,d_2,\cdots ,d_n) is said to be potentially K r+1-graphic if there exists a realization of π containing K r+1 as a subgraph. In this paper, we further investigate a number of new conditions for π to be potentially K r+1-graphic, which imply some previous results in [14,10,11] and the values of σ(K r+1, n) for n ≥ 5r/2 +1, which was conjectured in [2] and was confirmed in [6,7,8,3]. Moreover, we also determine F(4), the set of all graphic sequences π=(d1, d2, …, dn) with n ≥ 5 and d5 ≥ 4 so that π is not potentially K5-graphic.