Based on the relationship between financial capability and financial efficiency, over-investment behaviors are discriminated for 68 banks from 2007 to 2013 in China, and a hypothesis of Financial Service Feature is proposed to explain this phenomenon. Generally speaking, over-investment is very popular in all banks. The Hypothesis of Financial Service Feature is true really. Investors overly invested in banks in order to control those bank’s financial resources which are accumulated in the financial services. The investments in the Nationalized banks and City banks are the most excessive. The investments in unlisted banks are more excessive than that in those listed banks. The hypothesis of Financial Service Feature is verified in the Nationalized banks and City banks, including in those unlisted banks. As for the different investment channels, the debt capitals are most extravagant. But equity investors have the strongest motivation to control the financial resources. It’s useful to relieve the over investment and correct the harmful investment motivation by improving the regulation and information transparency.