The berth operability determines the throughput capacity，thus it is very important for the engineering design. In international projects，owners and consulting engineers usually put forward clear requirements on the berth operability. However，the domestic project’s requirements for the berth operability are relatively vague. Investigating the analysis method of the domestic berth operability days，we find that the domestic statistical superimposed analysis method is usually used to deduct different factors （such as wind，waves，currents，etc.） affecting the number of days that the berth can operate based on the operation standards. This method is relatively inaccurate. Then，in conjunction with international actual engineering，we take the LNG berth as an example to introduce the overall process analysis method for the berth operability and elaborate the overall process analysis method and its two major points，which provides a reference for the calculation of the berth’s throughput capacity.