In the process of exploring the essence of light, Newton initially agreed with the particle interpretation of light while Huygens argued for the wave theory. Hence, these two theories had been disputed in Newton’s time. In the beginning people accepted the particle theory, but after Thomas Young’s experiment and Augustin Jean Fresnel’s experiment, people began to accept the wave theory. Until Einstein proposed the quanta concept, which was later called photon, and, even later, De Broglie proposed the wave nature of matter, subsequently, people began using particle-wave duality to explicate all phenomena in micro world. Thus here appears a paradox: how can one particle exist in two forms? To solve this enigma, I have done some experiments; discover that moving photons create force; this effect reveal the phenomenon of light wave property - the inference fringes is caused by force which moving photons produced. The essence of light is particle but not particle-wave duality.