The complexity of control of large technical systems coupled with the time-consuming process of obtaining and processing of the factual data from the operational documentation contributes to the situation with discrepancies in the real state of the system and the status reflected in the documentation. This reduces the information entropy of the system and the number of incorrect management decisions. Thus, adoption of control solutions for large and complex technical systems is only possible, if they meet the conditions of the admissible value of the entropy. The task of monitoring of the information entropy of large complex technical systems should be solved with an automated control of quantifying the information entropy of the system, which leads to conclusion about a possibility of making control solutions based on the stored factual data. The paper describes the method of a qualimetric evaluation of the information entropy of large technical systems based on operational models of a semistructured content. This method is based on an automated analysis of a group of decision-makers of the factual content associated with the operational documentation generated during operation of the identified system. Use of the semistructured content model implements a universal interface with access to the factual data of the electronic documents, which reduces the number of the processing errors and increases the processing speed of the factual content. The latter reduces the total information entropy of the driven system.