According to ICRP Publication 60, the exposure of civil aviation aircrew to cosmic radiation in jet aircraft should be considered as occupational exposure. In order to evaluate the radiation environment of flight altitude, the cosmic radiation dose must be estimated by measuring or calculating. In this paper the cosmic radiation was introduced, and concept of computer program for calculation of cosmic radiation dose was described. The cosmic radiation effective dose of several flight routes calculated by using CARI-6, and the calculated results compared with the measured results. The present analysis shows that the effective dose is not directly measurable, and recently the computer cosmic radiation dose estimate system is practical tool for aircrew radiation exposure monitoring. At the present time, radiation environments in the atmosphere have been studied applying various ways. The computer simulation is a important tool. For aims of individual dosimetry. the recommended operational quantity by ICRP is the 'effective dose'. This is a quantity used for estimating the radiological risk, which involves not only physical but also radiobiological and other information. This includes, for instance, the fact that neutrons have a far higher biological effect than photons and that the radiation sensitivity of individual organs differs widely. The effective dose is thus not directly measurable, it has to be fully calculated, or be converted from measurements that represent an initial approximation to actual doses. The latter method requires what are known as particle spectra, i.e. the number of particles found in one of the many energy intervals. This information can only be obtained from computer simulation program calculations in the particular energy range that is significant in terms of dosimetry. Measurements with different, suitable experimental devices have been done and are done at different times, at different geographical locations and at different flight altitudes so that as accurate a physical model as possible is required which will find an adjustment of these measurements. So can't simply be used measurements taken in aircraft to measure the effective dose required by ICRP.