Vertical scale is an important feature to distinguish underwater real target from conventional scale simulation target. Aiming at the requirements of target scale estimation for small aperture array，a vertical scale estimation method for real targets is proposed. Vertical scale estimation is carried through the measured high frequency echo test data of the underwater vehicle scale model. The results show that the scale feature of the underwater real target can be estimated effectively through small aperture array，and different transmitted signals have different feature results. The experimental results show that the method is effective.