The longitudinal coherence properties of laser speckles are investigated. The properties are then utilized for three-dimensional (3-D) shape absolute measurement, bringing a feature that phase unwrapping is released. A sequence of speckle images is captured by a CCD camera at different longitudinal positions. The lateral displacement of the speckle can be obtained by calculating the correlation among the speckle images. According to the relationship between the longitudinal length and the lateral displacement, the absolute measurement of height from the object surface to reference plane can be realized. Additionally, the phase unwrapping process is released in data processing. A projection-lens system in the technique of projected digital speckle patterns is also released, because the laser speckle field is generated by a laser which illuminates on a frosted glass. The structure of the system is simple and convenient for implement. This technique is potential to be used in practice.