Many scholars have always been disputing whether there is a significant change in Einstein's philosophy of science.Some of them hold that Einstein changed his thought from empiricism to rationalism.Some argue that such a change did not exist.Still others think that Einstein's philosophy is imbued with a pluralistic tension.However, further studies from relevant logic and historical facts have proved that the transformation did happen.When making a study of a scientist's philosophical thought of science, we should distinguish between his own expression of his thought and his practice.The role of his philosophical thought of science upon his scientific activities is limited.