[en] The formation of DC-72 cyclotron magnetic field was carried out. The modeling and computer simulations of the magnet elements were used for preliminary choice of a cyclotron magnet structure. For exact isochronous magnetic field formation, at the nominal working point and correction of the field first harmonic, side sectors shims have been applied. The measured magnetic fields of the main magnet and correcting coils at different levels are used as inputs to the computer program in order to simulate different regimes of the working diagram. Satisfactory results have been obtained from calculations of the beam dynamics at the chosen working regimes with appropriate magnetic fields which were shaped with correcting coils and subsequently measured. This also allowed for mutual comparison of the simulated and measured data. The isochronous cyclotron DC-72 is intended to accelerate ions from H"- (A/Z=1, W=72 MeV/u) up to "1"2"9Xe"1"8"+ (A/Z=7.167, W=2.7 MeV/u). The cyclotron magnet has the pole of 2.6 m diameter and provides the working magnetic fields in the range from 0.9 T to 1.51 T for the given modes of the acceleration. A preliminary design of the magnetic field has been accomplished by the help of a model of the magnet which has been made in the scale 1:5 and mathematically simulated. The results achieved from the measurements performed upon the magnetic field of the final product are presented, too. (Author)