Background: Since phosphorus is the vital nutrient for plants, the evaluation of phosphorous fertilizers effects on yield and quality of valerian is necessary. Objective: In this research the effect of phosphorus solubilization bacterias as bio-fertilizers and phosphorous chemical fertilizer on quantity and quality yield of valerian was studied. Methods: This study conducted in the research farm of Institute of Medicinal Plants (IMP) through a factorial experiment based on a randomized complete blocks design with three replications. Factors of experiment included the inoculation bio-fertilizers factor in four levels: Azotobacter, Pseudomonas, mix of both and control (without inoculation), and also the phosphorous chemical fertilizer factor as super phosphate triple in three levels: 0, 50 and 100 kg ha-1. Results: The bio-fertilizers using had a significant effect (p≤0.01) on the most of studied quantity and quality parameters. Although, the bio-fertilizers using had a negative effect on the amount of valernic acid (%), because of the increasing of root dry weight, it led to a significant rising on yield of valernic acid per hectare. Phosphorous chemical fertilizer had a significant effect on valernic acid (%) (p≤0.01), yield of valernic acid (p≤0.05) and yield of fresh/dry weight of root and shoot (p≤0.01). Also, the result showed that maximum amount of root dry weight was obtained by using both of Azotobacter and phosphorous chemical fertilizers (100 kg ha-1). Conclusion: Azotobacter had a positive and significant effect on yield of valernic acid and also maximum yield of valernic acid was observed by this treatment.