Stability issue has a significant role in the design of structures; especially it becomes even much more substantial when the design deals with the thin-walled structures under complex loading condition, which is a combination of two or more loading types at the same time. The present research paper aims to analyse the stability region of the thin-walled beams with doubly symmetric cross-sections under combined loads simultaneously: axial force, uniformly distributed transverse loads and bending moments at the ends. A novel approach was proposed by the authors and the energy method was used to solve the problem. The final results are able to be represented by mean of not only generalized algebraic equations among the critical loads, but also by three-dimensional graphs. Based on a particular thin-walled beam as an example, the analytical results obtained by using a novel approach were in agreement with the numerical results of analysis by finite element method in the feasible computational software.