In order to expand the function of the orchard straw mulching machine and solve the problem of the shortage of organic fertilizer fertilization machine in a hilly orchard, a self-propelled orchard organic fertilizer strip-spreader was developed based on the straw mulching machine. The machine was mainly composed of the vehicle body and the strip-spreading device. The strip-spreading device adopted a telescopic structure, and the spacing of the strip-spreading was 1.8~2.7m, which was suitable for ditch fertilization or two-side strip spreading of organic fertilizer in orchard with row spacing of 3.0~4.5m or applying base fertilizer along the rows for field crops or spreading cultivation substrate in strips. The discrete element method was used to optimize the fertilizing outlet structure of the strip-spreading device, and the best XK type fertilizing outlet structure was decided. The strip-spreading test results showed that the fertilizing amount of the decomposed cow manure was ranged from 29.40t/hm2 to 53.10t/hm2, and the coefficient of variation was less than or equal to 15.48%. The amount of the mushroom residue applied was 21.45~75.00t/hm2, and the coefficient of variation was less than or equal to 6.57%. The determination coefficients of the fertilization quantitative models of the decomposed cow manure and the mushroom residue were 0.8713 and 0.9631, respectively. In the field test of orchard, the strip-spreader showed a good operation effect. The self-propelled orchard organic fertilizer strip-spreader can adapt to large-scale fertilization in a hilly orchard.