Abstract: The relationship of gas peak shaving capability and pipeline diameter is generally misunderstood in the pipeline design and operation management. Peak shaving capacity is one-sided affirmed increasing with pipeline diameter regardless of the pipeline shaving coverage. In this regard, depending on the pipeline peak shaving coverage, the impact of pipeline diameter on the peak shaving capability is investigated by month, day and hour separately. The pipeline diameter in relative to gas storage capacity is derived to prove that an optimal pipeline diameter exists for the pipeline adjusting the hour-peak to provide a maximum daily shaving capacity. This conclusion is verified using hydraulic analysis software, on the basis of an engineering project. Through mathematical derivation and quantitative calculation, aforesaid one-sided understanding is corrected, which will be a significant reference for gas pipeline design and construction management in the future.