The generation of squeezed vacuum quantum optical frequency comb is realized from a singly resonant synchronously pumped optical parametric oscillator (SPOPO) pumped by the second harmonic of a mode-locked femtosecond laser with a central wavelength of 815 nm. With the balanced homodyne detection system, the squeezing degree of the zero-order super-mode pulse is 3 dB and the real squeezing degree is 5.15 dB, which indicates that the experimental result is well consistent with that obtained by the theoretical model. The effects of the transmissivity of the output coupling mirror and the loss of the intra-cavity for the singly resonant SPOPO and the efficiency of the detection device on the squeezing degree are theoretically analyzed, which provides a guidance for the optimization of the experimental measurement of the quantum optical combs.