An enterprise development needs financial support. But at present, lack of funds rising has become one of important factors to restrict an enterprise development. Especially in the process of Middle and Small- sized Enterprises development, the most serious problem is lack of funds, together with absence of external financing sources, so internal financing becomes main means for their capital acquisition and long- run development. Many financing patters include internal cash flow financing, internal debt financing, internal equity financing and so on. Also relevant funds financing patterns are analyzed. Moreover, about the choices of financing sources and patterns, an enterprise should comprehensively consider such factors as its development conditions, financing risks and acquisition of economic benefits and so on,in order to make correct judgments.