The invention discloses an adjustable shielding net for improving a power frequency electric (magnetic) field around an overhead power transmission line. The adjustable shielding net comprises a vertical fixed pole (1) and a horizontal fixed pole (3) above, a vertical movable pole (2) is arranged at the upper end of the vertical fixed pole (1), the top end of the vertical movable pole (2) is connected with one end of a horizontal movable pole (4) above, the other end of the horizontal movable pole (4) above is arranged on one end of the horizontal fixed pole (3) above, the other end of the horizontal fixed pole (3) above is fixedly arranged at the upper end of the adjacent vertical movable pole (2), the vertical movable pole (2) is arranged at the upper end of another vertical fixed pole (1), and a movable connecting piece (10) is connected with shielding net horizontal lines (8) and shielding net longitudinal lines (9). The adjustable shielding net is simple in structure and convenient to install and adjust, the shielding net horizontal lines and the shielding net longitudinal lines are interwoven to jointly form a shielding net which can effectively form electromagnetic shielding, the density of the shielding net can be adjusted as required, and the usage range is wide.