A coaxial cable connector includes a connector body, a contact chamber, a copper sleeve, and an observation window opening. A central contact bore is formed inside the observation window opening and an insulation layer is set between the central contact bore and the contact chamber. The central contact bore has a notch formed in a side thereof close to the copper sleeve to receive a core conductor of the coaxial cable to insert therein. The central contact bore also has a stop wall that prevents the core conductor from extending beyond the central contact bore. An insulation block covers the central contact bore, and a window opening bolt is set in engagement with and thus closes the observation window opening to force a projection of the insulation block to depress the core conductor to engage the central contact bore for electrical contact therebetween.