To investigate the effects of the mixed addition of shrub and grass litters on the remediation of crude oil contaminated soil, a total of 9 types of mixture litters that mixed from 10 common shrub and grass species in northern Shaanxi were selected. The single-specific litter or litter mixtures were added into 15 g/kg crude oil contaminated soil at a proportion of 2% (litter:soil, w/w), and then a 150-day simulated necrophytoremediation experiment was conducted at the room temperature (20-25℃) with constant humidity. The results indicated that single-litter treatments significantly increased the degradation rate of the contaminants (the degradation rate of crude oil increased by 35%-58%) and the contents of nitrate nitrogen, available P and available K (36%-5600%), and most of the treatments significantly increased the activities of sucrase, urease, alkaline phosphatase and dehydrogenase by 40%-680% in the contaminated soil. In addition, the mixture of litters of Bothriochloa ischaemum with Periploca sepium and Sophora davidii, Lespedeza davurica with Artemisia gmelinii, L. davurica with Heteropappus altaicus and Artemisia annua or A. gmelinii with P. sepium could promote the degradation of crude oil and its components as well as the significant synergistic effects. As compared with the single-litter treatments, the degradation rates and the predicted values in these mixture treatments increased by 5%-28% and 5%-17%, respectively. At the same time, the antagonistic effects in these mixture treatments could weaken the supplement ability of soil available N (especially the nitrate N) and the stimulation effect of soil enzymatic activity (especially the activities of sucrase and dehydrogenase), which decreased by 6%-78% and 14%-67% as compared with the predicted values, respectively. In practice, the above mentioned mixture treatments could enhance degradation capacity of litter to contaminants, which still need to combine with other remediation methods to improve the biochemical properties of the contaminated soil. However, compared with the single-litter treatments, the mixing of litters of B. ischaemum with S. davidii, A. gmelinii with S. davidii or P. sepium with S. davidii significantly decreased the degradation rate of contaminants. Thus, to avoid their antagonistic effects in the remediation of crude oil contaminated soil, different litters should be separated. In general, adding mixed litters with high polyphenols, flavonoids, organic acids and P contents, low C content and C/P ratio, and high chemical diversity were more favorable to remove the petroleum contaminants in soil. However, the mentioned secondary metabolites from litters might be adverse to recovery of the nutritional conditions and enzymatic activities of the contaminated soil.