Expansive soil is a term of soil with a large potential for swelling and shrinkage when it experiences changes in water content. Pevement build on expansive clay which becomes the base layer of a building or pavement can cause structural problems on it, such as experiencing cracks and non-uniform decreases. Piles are chosen as one alternative for rigid pavement reinforcement systems. The piles is not soil improvement, but reinforcement. Plate deflection analysis was carried out on plate modeling measuring 70 × 30 × 2 cm and variations in the depth of erection of piles 10 and 20 cm in diameter 4 cm. Deflection is analyzed using the Beam on elastic foundation method. The purpose of the numerical analysis is to validate deflection that occurs in the laboratory. In this study, deflection was analyzed using various subgrade modulus reaction values (kv) to produce deflection which approached deflection in the laboratory. The value of kv used is kv correction, kv observation, and kv back analysis. The results for wet analysis plate without piles have kv 32525,36 kN / m3 from 4x kv corection and 11,77x kv of result, plate with piles length of 10 cm of 212202,381 kN / m3 25x kv correction and 20,77 kv of result, and plate with 20 cm piles of 665902,141 kN / m3 65x kv correction and 17,11x kv of result. Whereas in dry soil, the value of kv plate without piles equal to 823529,412 kN / m3 1x kv correction and 2,31 kv of result, kv plate with piles 10 cm is 1929824,561 kN / m3 15x kv correction and 23,56x kv of result, and kv plate with piles 20 cm is 1468428,781 kN / m3 7,5x kv correction and 12,5x kv of result. Based on the results of the analysis, Beam on Elastic Foundation method can validasion deflection result.