The international standard ISO 6954, prepared by Technical Committee ISO/TC 108, Mechanical vibration and shock, has experienced two versions: ISO 6954-1984, which gives the guidelines for the overall evaluation of vibration in merchant ships, and ISO 6954-2000, which gives guidelines for the measurement, reporting and evaluation of vibration with regard to habitability on passenger and merchant ships. There are significant differences between the two versions, although the two criteria are both applied now. The main purpose of this paper is to compare the current version with its predecessor, mainly for theoretical approach and practical measurement. Comparison between two versions by some key classification societies and relevant technical papers is introduced as well. The goal is to give some preliminary discussion about the application of the ISO 6954 code.