We got operational safety limit angle being able to affect operators or materials surrounding the center of vertical line of the hoist on working from the theoretical review and experimental result. Then we inferred the distance to about 1.2m-1.4m from the center which materials hanged on the hook were able to effect to the surround. Therefore, we got about $7^{circ}$ to the inclined or crossed operational safety limit angle of the crane with 6m lift. Also, we developed heisting rope automatic vertical controller which could control this kind of dangerous operation. And we did experiments again after establishing the inclined or crossed operational safety limit to $7^{circ}$. The result is satisfied.