In this paper line x-ray emission from aluminum plasma at wavelength within range of 5 - 7 angstrom was studied
numerically. The plasma was assumed to be produced by irradiating of aluminum target by long laser pulses
(1000 <i>ps</i> ≥ <i>τ<sub>p</sub></i> ≥ <i>50 ps</i>) at intensities up to <i>I</i> = <i>5×10<sup>16</sup>Wcm<sup>-2</sup></i>. The plasma hydrodynamics was simulated by EHYBRID
code. Using the data from this code and Saha-Boltzmann equation; the x-ray spectrum and total x-ray yield of the plasma
were calculated within the time scale of irradiation. The influences of laser intensity as well as pulse duration on the total
yield of x-ray line emission were investigated. The results show that, the emitted x-ray lines at the above wavelength
range has duration similar to that of the laser pulse and the total x-ray yield can be increased by increasing laser intensity
and pulse duration.