The invention provides a fluorescence-Raman synchronous block detector used for detecting elementary composition information and molecular structure information of to-be-detected blocky objects synchronously. The fluorescence-Raman synchronous block detector comprises a light source generation unit, a fluorescence excitation unit, a Raman excitation unit and a spectrum detection unit. The light source generation unit comprises a laser device, a nonlinear frequency doubling crystal used for converting laser beams into fundamental frequency light and doubling frequency light, and a beam splitting plate used for splitting the fundamental frequency light and the doubling frequency light. The fluorescence excitation unit comprises a first beam widening concave mirror and a first focusing convex mirror. The first focusing convex mirror is used for focusing the fundamental frequency light onto the to-be-detected objects to form small particles on the surfaces of the to-be-detected objects. The Ramen excitation unit comprises a second beam widening concave mirror and a second focusing convex mirror. The second focusing convex mirror is used for focusing the doubling frequency light to the small particles. The spectrum detection unit comprises a collection concave mirror, a first light sport cutting mirror group, a second light sport cutting mirror group, an off-axis paraboloidal mirror, a filtration unit and a spectrum analysis unit. The collection concave mirror is used for collecting reflected detection light signals. The spectrum analysis unit can acquire the molecular structure information and the elementary composition information according to Raman signals and fluorescence signals.