In this paper, the orthogonal experimental design method is used to study the influences of various factors on unstable water flooding development effects aiming at the seven geological reservoir factors and five engineering factors that influence the unstable water flooding development effects of anisotropic reservoirs. Twenty seven (27) experimental programs are proposed in this paper. Compared with conventional water flooding, most of them can increase the recovery efficiency in a certain degree and the best one can increase it by 2.73%. The visual analyses of range and variance on the experimental results indicate that the key factors affecting the recovery efficiency increase of unstable water flooding are working system, amplitude of fluctuation, relative waterflood frequency and waterflood timing; the moderate factors are reservoir rhythmicity, capillary pressure, water injection cycle and the wettability; and the minor factors are permeability ratio, rock compressibility, viscosity of crude oil and the coefficient of variation. The development engineering factors have the highest influence, followed by the geological factors. An optimum program is achieved after optimizing the development engineering parameters.The average EOR efficiency it achives is 3.83%,which is higher than the preferred plan in the orthogonal experimental design,the parameter optimization effect is scientific and rreasonable.