Punching shear is the main problem facing reinforced concrete (RC) flat slabs. There are many studies to investigate the punching shear of flat slabs in the normal cases, while there are very few studies that investigate circular flat slabs supported on circular columns. Therefore, this paper experimentally investigates the effect of: (1) Steel shear studs; (2) Steel stirrups; (3) Main reinforcement details and (4) Shear reinforcement arrangement on punching shear resistance of circular RC flat slabs. The experimental results by the authors were compared with the numerical results using ANSYS V. 15, the analytical results using ACI 318-19 [2] and ECP 203-2020 [6]. The obtained results show that punching shear strength increased when using steel shear reinforcement (studs and stirrups) by 9% to 57%. Toughness and displacement ductility improved by 31% to 333% and 85 to 121%, respectively. Both ECP 203-2020 and ACI 318-2019 codes are overestimated in calculating the ultimate failure load for the range of the studied variables in this research and not in general.