We have performed a micromagnetic modeling analysis of an abutted permanent magnet longitudinal biased spin valve head, In this design, the linear dynamic range of the head output is essentially unchanged with decreasing track width down to 0.5 mu m. Optimizing sensor height can yield significant signal enhancement, It has been found that the pinning field on the pinned layer of the spin valve structure has to be greater than a critical value, below which the output will decrease rapidly with decreasing the pinning field, while above that the signal output remains essentially unchanged, Well defined cross-track performance is found for this head design.