In view of the fact that the calculation precision Of the late stag6 field of the transient sounding ig commonly rather low, the present paper, on the basis of the odd-even character of the real and imaginary components of the frequerey domain electronagnetic field and the derivative character of the Fourler transform and using cosine transform, has realized the conversion of the electromagnetic field from the frequency domain to the time domain. It is shownthat the calculation of late-stage transient electromagnetic and apparent electrical resistivity with this algorithm has relatively high precision. This paper has emphatically dealt with the direct problem in arbitrary angle transient electromagnetic sounding of single dipole power supply multipoint measurement; and summed up its regularity.