Abstract The structures made of composite materials represent a very great part of research in aeronautical and aerospace engineering considering their specific characteristics in term of lightness and rigidity. During service these structures are subjected to changely environmental conditions that sometimes are extremely in term of temperature and humidity which cause residual stresses. The determination of this stress is highly significant for the reliability of the design stages and dimensioning. This study investigates the behaviour of thick composite laminates using the high order method through stresses calculation. The composite plate is subjected to mechanical solicitation and working in a hygrothermal environment. Temperature and humidity are taken into account in the calculation of stresses. Different simulations are carried out for different profile of temperature and concentration distribution (linear, constant, parabolic, etc.) to observe the response of structures.