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In this study, Si₃N₄/BN fibrous monolithic ceramics were successfully prepared by wet spinning extrusion and hot pressing, and the effects on its ablation performance and microstructure were studied. The samples were burned in an oxyacetylene flame for 60 s <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 30 to evaluate the ablation resistance. With the increase in ablation time, the fibrous monolithic ceramics exhibited specific mass and linear ablation rates, which show a trend of first increasing, then decreasing, and then increasing again. When the ablation time is 60 s <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 10, 60 s <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 20, and 60 s <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 30, the mass ablation rates of the fibrous monolithic ceramics are 1 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 10⁻⁵ mg/s, −8.3 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 10⁻⁶ mg/s, −6.7 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 10⁻⁷ mg/s, respectively; the linear ablation rates are 4.7 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 10⁻⁵ μg/s, −1.2 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 10⁻⁵ μg/s and 1.7 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 10⁻⁶ μg/s. After 60 s <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>×</mo></semantics></math></inline-formula> 30 of ablation, the surface oxides of the species are washed away by the oxyacetylene flame, revealing a porous coral-like structure with many cracks. A glass phase layer, predominantly constituted by sintering aids, envelops the Si₃N₄ ceramic surface on the ablated sample, serving as an effective barrier against additional ablation.