Abstract: As a kind of artificial stone， the fracture failure process of concrete must have some randomness owing to impacts caused by concrete placement. Based on the acoustic emission dynamic nondestructive detecting technology， the objectivity of special test phenomenan has been analyzed for both the crack propagation with deviation of notched concrete three-point bending beam and the failure load reciprocating increase and decrease of the reinforced concrete three-point bending beam. It is found from the experimental results that the cracks propagate around the coarse aggregate rather than along the prefabricated crack because the coarse aggregate is just poured in the prefabricated crack tip. When the ratio of reinforcement is too high， the failure load of the reinforced concrete will vary near the yield strength of the bar cyclicly. It is thus clear that the instable load of the reinforced concrete three-point bending beam specimen would depend on the level of the ratio of concrete reinforcement bar. The research results indicate that the acoustic emission technology can be taken as a new research method for damage and fracture of concrete.