In this paper, we use the density functional theory (B3LYP) method with 6-311g(d) basis sets to optimize the molecular structure of C ₅F ₁₀O and obtain the stable structure of its ground state. On this basis, the geometric characteristics, energy, frontier orbital energy levels, and infrared spectra of C ₅F ₁₀O under the different external electric fields (from 0 to 0.03 a.u., 1 a.u. = 5.142 × 10 ¹¹V/m) are studied by the same method. Under the same basis sets, the orbital composition and excitation characteristics of C ₅F ₁₀O are calculated and analyzed by the TD-DFT method. The conclusions show that as the electric field increases, the bond energy of 5C—15F and 4C=16O gradually decrease, their bond lengths increase. The charge of 13F atoms changes fastest, and it is easier to lose electrons under the action of electric field force. The potential energy of the molecule increases, and the stability gradually decreases. The energy gap E _Gvalue continuously decreases, and the molecules are more likely to be excited to participate in the chemical reaction. In the infrared spectrum, four absorption peaks are blue-shifted, and four absorption peaks are red-shifted. The excitation characteristics of the first 8 singlet excited states of the C ₅F ₁₀O are identified by the hole-electron analysis method. The excitation energy of the first excited state increases slightly, and the wavelength decreases, and blue shift occurs. The excitation energy values of the other excited states decrease, their wavelengths increase, and red shifts occur. Because the electrons in C ₅F ₁₀O become easier to excite, the stability of the system is lower.