Deep lava maybe contain petroleum and natural gas or CO2 gas, it is very important to find lava but the lava is in deep stratum and has complex structure, so it is difficult to find lava stratum. There are some methods to predict where the lava is but some problem also is in them such as the precision of recognition and forecasting is not high. A generic algorithm with adaptive and floating-point code is proposed to overcome disadvantages of the genetic algorithm and BP algorithm. This algorithm is combined with BP to give GA-BP mixed algorithm which has higher accuracy and faster convergence speed. The new algorithm also provides improved predict accuracy of lava reservoir. An example shows the validity and feasibility of this algorithm.