The invention relates to the technical field of supports, in particular to an adjustable fixing support for installation of instruments and meters. The adjustable fixing support comprises a clamping and fixing mechanism, an angle adjusting mechanism and a base connecting mechanism, the angle adjusting mechanism is arranged at the top end of the base connecting mechanism, and the clamping and fixing mechanism is arranged at the top end of the angle adjusting mechanism. The angle adjusting mechanism comprises a stand column, a ball head, supporting rods, third springs, rotating discs, gear rings, gear columns, friction columns and sliding beads. The ball heads are rotationally connected to the inner side of the top end of the stand column, the gear columns are rotationally connected to the inner side of the stand column, the friction columns are fixedly connected to the top ends of the gear columns, and the sliding beads are rotationally connected to the inner sides of the friction columns. According to the adjustable fixing support, through the arranged angle adjusting mechanism, when the sliding beads are attached to the ball head, the ball head can rotate freely, the placement angle of the instruments and meters can be adjusted conveniently, placement of the instruments and meters under different conditions is met, and the instruments and meters are taken and used more conveniently.