This parametric study used finite element method (ETABS 2019), on 20 elliptical reinforced concrete cantilever deep beam specimens that have rectangular sections. Five parameters were taken into consideration: beam height, beam width, concrete compressive strength, load position and load type. Results showed that when the beam height was increased by 12%–66.5%, the negative and torsional moments and load capacity increased by about 11.23%–76.33%, 11.2%–77% and 11.1%–78%, respectively, whereas deflection decreased by about 15%–39%. The negative and torsional moments and load capacity increased by 26.13%–166.53%, 27%–172.5% and 28%–180%, respectively, and a decrease in deflection of about 1.73%–2.3% took place when beam width increased by about 14.3%–81%. In addition, increasing the compressive strength of concrete by 7.5%–36% led to an increase in the negative moments, torsional moments, load capacity, and deflection by about 8.22%–19.2%, 8.7%–20.4%, 9.4%–22% and 4.7%–7.1%, respectively. When changing the load type from concentrated to uniformly distributed over a third of the span’s length, two-thirds of the span’s length and then over the full span’s length, the negative moments increased by 5.23%, 8.47% and 52.67%, whereas torsional moments decreased by 1.1%, 1.12% and 16%, respectively. Finally, placing the concentrated load at a distance of 0.75, 0.5 and 0.25 of the span lengths led the negative moments to increase by 56.9%, 102.3% and 110%, respectively, whereas torsional moments decreased by 8.64%, 25%, and 58.3%, respectively. The load capacity increased by 87.5%, 243.75% and 556.25%, respectively, accompanied by a decrease in the deflection of the free end by 3.24%, 17.65% and 49.8%, respectively.