In order to assess the level of pollution caused by waste from the slaughterhouse of the city SidiSlimane, the aim of our study was to perform a statistical study by principal component analysis (PCA) of wastewater drained by the Oued Behtriver (Morocco). To do this, a series of analysis physicochemical parameters was carried out from ten urban wastewater collectors (C1, C2, C3, C4, C5, C6, C7, C8, C9, C10), tank located inside the slaughterhouse and collector carrying domestic wastewater mixed with wastewater from the slaughterhouse during the period November 2012 and August 2013. The analysis performed as COD (chemical oxygen demand), BOD5 (biological oxygen demand), SS (suspended solids),Fecal Coliforms bacteriological parameters (FC) and Fecal Streptococci (FS). For bacteriological parameters, there is increased from upstream to downstream in fecal contamination of fecal coliforms (FC) and fecal streptococci (FS). Statistical analysis provided us according F1XF2 60.8% of the total variance and has confirmed a strong correlation between the (physical and chemical parameters - months) (M1, M2, M3, M11, M12) to months (M4, M5, M6, M7, M8) which results in a decrease in oxygen and an increase in pollution parameters. According F1 X F2 giving 56.86% also confirms a strong correlation between the (physical and chemical parameters - stations) and informs us that there is more pollution from upstream stations C1 to C10 to the downstream stations P2 andP1 (outfall effluent from the slaughterhouse).