The theme of this thesis is, as the title says, the calculation and construction of a telescopic crane. The introduction briefly explains the characteristics of the crane and according to which requirements it was dimensioned. The second chapter contains the calculation of crane parts essential for its stability and functionality. First, we started with the dimensioning of the connecting rod of the main cylinder. The main cylinder enables the lifting and lowering of the crane boom. Dimensioning was carried out with regard to buckling. The connecting rod is most exposed to buckling at the maximum crane angle. Dimensional control and buckling control for the case of maximum force in the cylinder were checked. The maximum force in the cylinder occurs when the crane is in a horizontal position, because then the bending moment is the largest. The required connecting rod bolt is selected. The next element to be calculated was the crane boom stand. Considering the load acting on it, the necessary bolt is selected. Dimensioning of the weld was carried out and its stress was controlled in order not to separate the stand from the base plate. Next in line was the calculation of the screws. 36 screws, size range M20, property class 5.8 were selected, whose degree of safety against breakage due to fatigue of the material corresponds to the required one. Last, the crane boom was dimensioned considering the maximum bending moment. The allowable crane boom stress is 50% of the yield strength to ensure that the actual stress does not cause plastic deformation. At the end, the internal working principle of the crane, which consists of a pulley system, is briefly explained.