NOVELTY - Manufacture of 5-norbornene-2-spiro- alpha -cycloalkanone- alpha '-spiro-2"-5"-norbornene involves reacting carbonyl compound (I) and amine compound (II) in an acidic solvent which contains formaldehyde derivative and acid (VI), obtaining reaction solution comprising Mannich base (III) in the acidic solvent, adding organic solvent, base and diene compound (IV) to the reaction solution, heating, reacting the Mannich base with the diene compound, and forming 5-norbornene-2-spiro- alpha -cycloalkanone- alpha '-spiro-2"-5"-norbornene (V).    USE - Manufacture of 5-norbornene-2-spiro- alpha -cycloalkanone- alpha '-spiro-2"-5"-norbornene. Uses include but are not limited to raw material for manufacturing acid dianhydride monomer for polyimide production, film for flexible wiring board, heat-resistant insulating tape, protection coating agent of semiconductor, liquid crystal aligning film, transparent conductive film for organic electroluminescent device, flexible substrate film, film for touchscreen, transparent conductive film for organic thin-film solar cell, interlayer insulation film, etc.    ADVANTAGE - The method efficiently provides 5-norbornene-2-spiro- alpha -cycloalkanone- alpha '-spiro-2"-5"-norbornene with high yield.    DETAILED DESCRIPTION - Manufacture of 5-norbornene-2-spiro- alpha -cycloalkanone- alpha '-spiro-2"-5"-norbornene involves reacting carbonyl compound of formula (I) and amine compound of formula (II) in an acidic solvent which contains formaldehyde derivative and acid of formula: HX (VI), obtaining reaction solution comprising Mannich base of formula (III) in the acidic solvent, adding organic solvent, base and diene compound of formula (IV) to the reaction solution, heating, reacting the Mannich base with the diene compound, and forming 5-norbornene-2-spiro- alpha -cycloalkanone- alpha '-spiro-2"-5"-norbornene of formula (V). The usage amount of base is 1-20 molar equivalents of the acid. The content of the acid in the acidic solvent is 0.01-0.075 molar equivalent of ketone group in the carbonyl compound.    R1,R2=H, 1-10C alkyl or F;    n=0-12;    X=F, Cl, Br, I, CH3COO, CF3COO, CH3SO3, CF3SO3, C6H5SO3, CH3C6H4SO3, HOSO3 or H2PO4;    R3=1-20C linear saturated hydrocarbyl, 3-20C branched saturated hydrocarbyl, 3-20 cycloparaffin or hydroxy;    or two of R3=pyrrolidine ring, piperidine ring, piperazine ring or morpholine ring;    X-=F-, Cl-, Br-, I-, CH3COO-, CF3COO-, CH3SO3-,CF3SO3-,C6H5SO3-, CH3C6H4SO3-, HOSO3- or H2PO4-;and    R4=H, 1-10C alkyl or F.