In order to analyze and compare the remediation effects of the different biochars on crude-oil contaminated soil in eastern Gansu Province of the Loess Plateau, three types of biochars were fabricated from maize straw (JYB), wheat straw (JXB), and apple tree branch (JYB), together with the indigenous plant, Calendula officinalis, were taken as tested plant (J) to do the in situ ecological restoration for four months in the second oil production plant of the Changqing Oil Field Company. The changes of environmental factors, including soil total petroleum hydrocarbons (TPH) degradation rate, plant growth indices, soil physicochemical traits, enzyme activity, and soil microbial community structure were investigated by the conventional methods. The soil TPH degradation rate in the JYB[(59.89±2.23)%] and JGB[(58.17±1.89)%] treatments was relatively higher than that in the JXB and J treatments (P < 0.05). The plant height, plant aboveground and underground dry weight of Calendula officinalis, as well as its rhizospheric soil available N, available P, available K, and activity of soil dehydrogenase and polyphenol oxidase in the JYB, JXB, and JGB treatments were significantly higher than that in other treatments. While compared with JXB treatment, the plant root length, soil catalase and urease activity in JYB and JGB treatments were significantly increase by 23.81%、18.89%, 153.12%、80.13% and 188.66%、117.45%, respectively(P < 0.05). Furthermore, the dominant genera of soil microbial community with capacity of crude-oil degradation in the JYB and JGB treatments, including Sphingomonas, Oleispira, Simiduia, Salinimicrobium, Acinetobacter, Rhodococcus, Alcanivorax, and Nocardia, were significantly higher than that in the JXB and J treatments (P < 0.05). All of the results mentioned above indicated that the soil microbial community structures in the JYB and JGB treatments were different from that of the JXB and J treatments, which could be affected by relatively higher value of soil polyphenol oxidase activity (R²=0.9786, P=0.001), soil dehydrogenase activity (R²=0.9713, P=0.005), soil available N (R²=0.6112, P=0.046), Shannon index (R²=0.7311, P=0.036) and Chao1index (R²=0.6361, P=0.041) of soil microbial community, might be the reason why the soil TPH degradation rate in the JYB and JGB treatments was relatively higher than that of other treatments. Consequently, we proposed that maize straw biochar and apple tree branch would be preferred as the crude-oil contaminated soil remediation conditioner for phytoremediation in eastern Gansu province of loess plateau.