Abstract: The data of secondary ion mass spectrometry (SIMS) of coal are very complicated, which is attributed to the complexity of coal both in chemistry and in ionization. The exact interpretation of the spectra derived from coal,however, is very important fo understand the features or compositions of coal. The experiments of a typical coal sample were conducted by means of a secondary ion mass spectrometer with relatively high mass resolution (R≥7500,（28）Si),The goal of the whole work is to interpret all peaks in the obtained spectra,in order to acquire the basic but exact information on coal SIMS and develop the model spectra of coal SIMS. This paper as the first section of the goal shows that 20 sorts of different composltions of positive ions exactly exist within mass range from m/z 1 to m/z 20,and 26 different compositions of negative ions appear from m/z 1 to m/z 31. Some compositions of ions,such as H3N+ (m/z 17.0272, tested in this work),H4N+ (m/z 18. 0355 ), H,N- (m/z16.0187), NH- (m/z15. 0107 ), H3O+ (m/z19. 0192), H(18)O- (19. 0084 ), CNu (m/z26. 0036 ) and Ca++ (m/z19. 9805 ), have been distinguished for coal SIMS for the first time. The abundance patterns of the homogenous ions and the abundance differences between positive and negative species are discussed in detail. The potential measuring some isotopic ratios, such as (18)O- /(16)O- (O. 214: 100, tested in this work), is also deliberated.