Thick frequency selective surface has potential applications in the stealth curved streamlined radomes because it has advantages in broadening bandwidth and overcoming multi-layer FSS shortcoming of complex structure and low transmittance of central frequency due to the cascade. However, there are a drift of central frequency in a wide range of incident angle and an unsteadiness of polarization at big incident angle. To solve the problem, in this paper we provide a novel Y element thick FSS. The structure is analyzed using mode matching method. The bandwidth, the central frequency and its transmittance of the structure are investigated when some parameters including the incidence angle of TE and TM waves and the polarization at big incident angle are changed. The novel Y element thick FSS has better transmission properties with polarization independence and incident angle independence. The novel structure provides a valuable reference for the application in stealth curved streamlined radomes.