Porous silicon was prepared by anodic reaction. The process was controlled by current density and etching time an the thickness change and the room temperature PL was measured. The thickness of porous silicon was increased with etching time and was decreased after critical time. It was the same as increasing current density. It needed only 15 sec to electropolish the surface of porous silicon above current density 70 mA/cm2. We can understand that increasing etching time leads narrow size of Si column by porous silicon formation mechanism. And the sample with narrow Si column revealed PL blue shift. The specimens were heated in the range of 300-1000$^{circ}C$ in order to see PL changes. The heat treatment was proceeded in H2 atmosphere vacuum system to avoid oxidation. The PL was disappeared above 600$^{circ}C$. In high temperature some sintered Si columns were observed in SEM photography. There was no difference of -Hx bonds which was suggested as evidence of hydride compounds luminescence between 500$^{circ}C$ and 600$^{circ}C$. Thus it is concluded that quantum confinement is major factor of PL of porous silicon.