Nanostructured phosphorous-alloyed Bi2Te3 thick films have been prepared by electrochemical deposition. The average grain size of the films was calculated to be 14-26nm based on Scherrer's equation. The effect of P on the Seebeck coefficient of the Bi2Te3 thick film was investigated. The results show that P-alloyed thick film has n-type conductivity with the Seebeck coefficient of -35 mu V/K. The correlation between P site occupancy in the crystal and the Seebeck coefficient was discussed.