This paper focusing on requesting low quality、small volume and high heat conduction of the instrument, applies theoretical analysising and thermal simulation calculation to support and guidance the stuctual desigh. This desigh method achieves the effective heat dissipation instrument of low costs, this instrument is reasionable because of the experimental verification. This desigh mode of combination of theoretical calculation and theral analysis can guide the structural desigh , the mode provides the derection of thermal desigh of structural.