A frequency upconversion imaging based on Hadamard coding is presented to remove the distorting effect on condition that the pump beam is tightly focused to optimize the conversion efficiency. The distortion caused by the convolution between the object field and the pump field is ascribed to the point spread function effect. In order to remove the blurring in an upconversion imaging system optimized by tight focused pump, the object is encoded by measurement matrices and the corresponding intensity of the converted field is measured. Thus the intensity distribution of the object can be calculated accurately by the measurements and the measurement matrix. The signal-to-noise ratio (SNR) is improved by employing the Hadamard matrix since the intensity of measured converted signal is far larger than the intensity of each pixel. The experimental results show the proposed method removes the distorting effect caused by the convolution. The converted image still has sharp edges on condition that the conversion efficiency is optimized by tight focusing the pump beam.