The invention discloses a test method and device for seabed cable tensility torque which can use horizontal and vertical ways, characterized in that the device comprises following components: (1) a fixed clamp for clamping the seabed cable, (2) an optical cable sample for the tested seabed, (3) a measuring device for displacement, (4) a rotatable clamp with an angle sensor, (5) a stretching sensor, (6) a counter poise and counter poise bracket, (7) a stretching converter, (8) an angle converter, (9) a displacement converter , (10) a centre processor, (11) a light power meter, (12) light source. After the method respectively processes optical connection and electrical connection for the test instruments and devices and forms the integral test devices, the method opens the light source and a stretching tester to observe and record the parameters of the light declining quantity, the tensility, the flexible strain capacity, the rotating direction of the cable and the angle of the seabed cable. The advantages of this invention is taking the parameters obtained by the test as import scientific foundation for research, design, production, technique and construction and maintenance of guide of the seabed cable for the leaders and scientific stuffs developing the relevant working decision.