Laser produced x-ray are having variety of applications. X-ray emission from copper plasma produced by a sub-nanosecond Nd: glass laser have been studied as a function of distance of the target from the best focus position. Optimization of soft (0.7 – 1.56 keV) and hard x-ray (3- 5 keV) emission as a function of the laser focal position has been undertaken. The x-ray line emission in the spectral range of 7.7 Å – 9.6 Å range with respect to the laser focal position is important for applications and has been separately measured. It is observed that the maximum soft x-ray emission is away on both side of the best focus while hard x-ray shows peak close to best focus position. The line emission intensity variation with respect to focal position also exhibits the double hump variation with varying focal position. This indicates that the line emission is a strong function of plasma volume rather than laser intensity.