Aimed at some existing disadvantages of magnetic fluid seal,for example,limited bearing capacity of magnetic fluid seal,harder to machine and assemble and high requirements in precision,a new magnetic fluid seal with flexible pole piece was presented.By using ANSYS finite element software,numerical model was established for the magnetic fluid seal with flexible pole piece,the distribution of magnetic field and pressure bearing capacity were analyzed and compared with traditional ones.By using orthogonal test method,the influence factors on sealing performance were studied and optimized,such as thickness and length of flexible pole piece,relative magnetic permeability,thickness of coating,thickness of sofa iron and other parameters,and etc.The results show that as compared to traditional ones,the magnetic fluid seal with flexible pole piece has better seal performance.Relative magnetic permeability of flexible pole piece has the greatest influence on pressure bearing capacity,and the next factors orderly are thickness of flexible pole piece,thickness of sofa iron and length of flexible pole piece.Thickness of coating has minimum impact for seal ability.As compared with traditional ones,after optimization,the seal performance of magnetic fluid seal with flexible pole piece is improved for more than 50%.