This paper deals with the modernization of the hydraulic drive control system of a trencher, which includes the design of a new control system and the simulation of the operation of the drive. This modernization extends the service life, but also the efficiency and productivity of the machine itself. At the beginning, it will be explained what exactly trenchers are and what they are used for, the characteristics of the Vermeer T800B trencher on which the modernization will be carried out will also be described and the description will be focused on its drive. Furthermore, the application and the advantages and disadvantages of hydraulic systems will be described, and an insight into the hydraulic drive of the machine intended for modernisation will be given. The ways to solve the problem of trencher control will be considered and we will offer the reasons for choosing a particular method. Then, system will be mathematically described and the synthesis of the PID controller of the hydraulic system will be presented after that, a simulation of the described system will be performed using FluidSIM simulation tool, from the company FESTO. We will analyze the results obtained by the simulation and compare them with the previous management method. In this paper, we will also discuss the design of the PCB board for the drive controller, but will also touch on some other upgrades that will be done on the machine in the future, like designing a device to measure the trenching depth, and the design of a dump truck backfilling conveyor.