Abstract: Biological sequence motif detection is a complex problem in bioinformatics,it is barely possible to design a method with the ability of discovering all motifs in biological sequences.In the paper,in order to detecting motifs,the precision of motif detection has been increased by embedding the statistical estimate into immune genetic algorithm.The diversity of population has been solved by designing a substitution operator according to fitness and density probability of individual.The algorithm search speed has been improved by using Gibbs Sampler to breed seed.Finally,An approach based on immune GA and Gibbs Sampler for biological sequence motif detection has been constructed.The algorithm not only sufficiently exerts the advantages of the two algorithms,but also solves the contradiction between the computational speed and precision.The experiments show that the algorithm is effective.