Portable mechanical arm with function of accurately positioning object

The invention relates to a portable mechanical arm with the function of accurately positioning an object, which comprises a fixed base and a rotary base, wherein a big arm is connected to the rotary base; an end of the big arm is connected to a small arm; an end of the small arm is connected to a mechanical hand fixed platform; a mechanical hand rotary platform is mounted on the mechanical hand fixed platform; an end of the mechanical hand rotary platform is connected to two flexible mechanical fingers; a grab positioning sensor is mounted on the mechanical hand rotary platform; and the grab positioning sensor comprises two parts, one is a color camera used for positioning a center of the object and the other is a point-shaped laser tube used for combining with the color camera to determine the distance between the mechanical hand and the object to be grabbed based on the triangle ranging principle. According to the invention, the weight of the end of the mechanical arm is greatly reduced by combining direct transmission, connection rod transmission, synchronous transmission and pull ling transmission; and at the same time, the movable range is ensured to be larger, thus the contradiction between the freedom degree amount and the effective load of the mechanical arm is solved.