The bottom structures in shaking bioreactors have great influence on the flow field characteristics. In this work, four kinds of bottom structures, such as conical bottom, ellipsoid bottom, flat bottom, and sphere bottom are presented, and the mixing, dissolved oxygen and shear strain rate of bioreactors with different bottom structures are simulated by means of CFD. The simulated free surface shapes were verified by the observed images in video. The results showed that turbulent kinetic energy were 0.0014 m(2).s(-2), 0.0016 m(2).s(-2), 0.0012 m(2).s(-2) and 0.0011 m(2).s(-2), and the values of k(L)a are 2.6h(-1), 2.9 h(-1), 2.1 h(-1) and 2.0 h(-1) for the conical bottom, ellipsoid bottom, flat bottom and sphere bottoms, respectively. This indicates that the mixing and dissolved oxygen characteristics of the bioreactors with the ellipsoid and conical bottoms were superior to the flat and sphere bottoms. The shear strain rates in the bioreactors with different bottoms were mainly in the range of 8-10 s(-1). The highest average shear strain rate was found in the bioreactor with the flat bottom, and it was still in the low shear strain rate range and suitable for the growth of shear-sensitive cells.