A program for analysis of the time-of-flight analyzer characteristics is described. It operates with actual instrument parameters (inter-electrode distances and electrode potentials), which makes it easier to use the program on-line during both the instrument operation and adjustment. Some results of calculations as applied to the existing prototype analyzer are given. It is inferred that the electrostatic mirror needs updating, i. e., going to a two-stage one. A mass spectrum of insulin taken at a resolution R > 15 000 is presented.