Abstract: The direct analysis of GBW07123, garnet and petrified wood were investigated using the homemade laser ablation and ionization time-of-flight mass spectrometer (LAI-TOFMS). Samples were analyzed in pressed pellet forms. Parametric studies were conducted on the mass spectrometer with respect to laser power density, pressure of the buffer gas and repelling modes of the pulse. The tentative methods used to determine elemental concentration and relative elemental concentration of samples were also discussed. In the research, Mn was chosen as the referenced element. In LAI-TOFMS, elemental concentration was calculated by RSCs (relative sensitivity coefficient) and the concentration of Mn, while relative elemental concentration was related to the mass of the measured element and its intensity in the spectrum. In ICP-MS and XRF, relative elemental concentration was the ratio of concentration of measured elements to that of Mn. Analytical process and results of LAI-TOFMS, ICP-MS and XRF were compared. The results presented by LAI-TOFMS are in relatively good agreement with that obtained from ICP-MS and XRF. Moreover, LAI-TOFMS allows for rapid elemental analysis due to its simple sample preparation, almost no contamination to sample and little sample consumption. Ultimately, LAI-TOFMS offers the capability of semiquantitative mineral direct analysis.