In order to extract the relative elevation information of multi-objects from the echo waveform of the spaceborne earth observing laser altimeter with large- footprint, a Levenberg- Marquardt- based Gaussian decomposition algorithm is used to separate the waveforms, and a full-waveform acquisition system is developed for multi-objects. Experiments on the ground-based multi-objective distance information acquisition are carried out to verify the decomposition algorithm. The experimental results show that the calculated relative distance error of multi-objectives is less than 0.03 m which reveals the effectiveness of algorithm in separating multi-objects from echo waveforms and the validity of the large-footprint full-waveform acquisition system for expracting the relative distance informention of mulit-objects. The research is useful for the design of space-borne laser altimeter system and the study of data processing algorithm.