To investigate the effect of nitrogen fertilization forms (ammonium sulphate and calcium nitrate) and some bio-stimulants (humic acid, fulvic acid, EM and yeast extract) under high temperature on flowering characters, yield and its components of cucumber (Cucumis sativus L.) cv. Prince, two field experiments were carried out in a private farm at El-Mahalla El-Kubra- Gharbia governorate during the two successive summer seasons of 2011 and 2012 Results showed that the (50%NH₄ + 50%NO₃) treatment of N-forms increase No. of female flowers, fruit setting, early and total yield significantly, while  No. of male flowers and sex ratio decreased significantly. Foliar spraying of cucumber plants with bio-stimulants significantly increased the mean values of the No. of female flowers, fruit setting early and total yield as compared with the control treatment. The best foliar application were yeast extract at 10 g/l or effective Microorganisms (EM) at 20 ml/l. Therefore  we recommend using nitrogen fertilization as (50% NH₄ +50% NO₃) combined with spraying yeast extract at 10 g/l or effective Microorganisms (EM) at 20 ml/l under high temperature conditions.