NOVELTY - Controllably loading metal platinum (Pt) on surface of multiple wall nanotube (MWNT) via in situ synthesis includes adding MWNT into triethylene glycol; processing ultrasonic treatment; adding Pt acetylacetonate into the suspension; continuously processing ultrasonic treatment; heating; adding nitrogen or argon to remove oxygen; refluxing; cooling; adding absolute ethyl alcohol into the reactant for diluting the solution; centrifuging; cleaning the centrifuging product by absolute ethyl alcohol; vacuum drying; and obtaining Pt/MWNTs nanomaterial.    USE - Controllably loading metal Pt on surface of MWNT via in situ synthesis to obtain Pt/MWNTs nanomaterial (claimed) useful as cathode/anode catalyst e.g. of direct methanol fuel cell, and useful e.g. for gas reforming, pollutant treatment, organic material splitting decomposition, and organic material synthesis.    ADVANTAGE - The method is simple and has high efficiency.    DETAILED DESCRIPTION - Controllably loading metal Pt on surface of MWNT via in situ synthesis comprises:    (A) adding 10.0 mg MWNT into 20.0 ml triethylene glycol; processing ultrasonic treatment for 5 minutes via ultrasonic apparatus having ultrasonic power of 150-200 W; adding 10.0-40.0 mg Pt acetylacetonate into the suspension; continuously processing ultrasonic treatment for 15 minutes under ultrasonic power of 150-200 W; heating at 220-296 degrees C with heating rate of 2.5 degrees C/minute under the condition that rotation rate of magnetic force stirring is 200-350 revolutions/minute; adding nitrogen or argon to remove oxygen; refluxing for 30 minutes; and cooling; and    (B) adding absolute ethyl alcohol into the reactant for diluting the solution, where amount of absolute ethyl alcohol equals the usage amount of triethylene glycol; centrifuging at 8500-10000 revolutions/minute for 3-7 minutes; cleaning the centrifuging product by absolute ethyl alcohol; vacuum drying at 55-80 degrees C for 8-12 hours; and obtaining Pt/MWNTs nanomaterial.