  The partition function in Matrix theory is constructed by Euclidean path
integral method. The D0-branes, which move around in the finite region with a
typical size of Schwarzschild radius, are chosen as the background. The mass
and entropy of the system obtained from the partition function contain the
parameters of the background. After averaging the mass and entropy over the
parameters, we find that they match the properties of 11D Schwarzschild black
holes. The period $\b$ of Euclidean time can be identified with the reciprocal
of the boosted Hawking temperature. The entropy $S$ is shown to be proportional
to the number $N$ of Matrix theory partons, which is a consequence of the
D0-brane background.
