A device and method for measuring the coefficient of thermal expansion of composites based on digital recordings of the indicating laser spot displacement has been developed.  Specific holders for support of the test object and an optical arrangement of the dilatometer are proposed to measure the deformation of the carbon fiber reinforced compositetubes due to temperature changes. The advantages of the system include high sensitivity and the ability to examine composite tubes with varied length (from 0,2 m to 2 m) with high accuracy. A special heating system for temperature changes in examined objectsbased on conductivity of carbon fiber has been developed. The sensitivity of the dilatometer can be adjusted in according to the size of examined objects.