This study was conducted during 2014 and 2015 seasons to test the effect of different concentrations (0.05 & 0.1 & 0.2%) and frequencies of application (twice or thrice) of potassium silicate on fruiting of Navel orange tree s grown under Bani-Suef environmental conditions.  Carrying out two or three sprays of potassium silicate at 0.05 to 0.2% had material promotion on all vegetative growth aspects, leaf pigments and nutrients, fruit setting %, yield and both physical and chemical characteristics of the fruits over the check treatment. The promotion was related to the increase in both concentrations and frequencies of application of potassium silicate. All the investigated characteristics were unaffected by increasing concentrations of potassium silicate from 0.1 to 0.2% and frequencies of application from twice to thrice.   Carrying out two sprays of potassium silicate at 0.1% on the middle of March and April gave the best results with regard to yield and fruit quality of Navel orange trees grown under Bani-Suef conditions.