The internal stresses in the continuous tungsten-fiber reinforced copper-matrix composite were examined by the Neutron stress measurement method. The Neutron diffraction apparatus ND1, which is abbreviated from the Neutron Diffraction system No.1 designed and manufactured by the National Nuclear Energy Agency in Indonesia (Badan Tenage Nuklir Nasional, BATAN), was used in the present study. The most common 3-axes measurement method with Hooke’s equation was only possible to measure about 110 plane, because the tungsten fiber became the situation of heavy 110 orientation. Thermal stress alterations caused form low temperature cycling was measured by in-situ stress measurement method making use of a cryostat system. The thermal residual stresses in tungsten-fiber longitudinal direction were compressive state in every stage. Results of in-situ thermal stress measurement were good agreed with a calculated result of simple elastic theory in elastic area.