The transport of runaway electrons in hot plasma can be comparatively easily measured by steady state or perturbation experiments, which provide runaway electron diffusivity Dr. The runaway diffusion coefficient has been obtained using four methods: (1) Dr is deduced from Plasma shift experiment; (2) Dr is deduced from its sawteeth oscillations behaviors of HXR flux and of SXR intensity; (3) Dr is deduced from microwave radiation intensity sawtoothing behaviors; (4) Dr is deduced from hard-X-ray bremsstrahlung spectra. The diffusivity can be interpreted in terms of a magnetic fluctuation level. The internal magnetic fluctuations level (b～r/BT) is estimated to be about (2—4)×10-4 in the HL-1M plasma. The results presented here demonstrate the effectiveness of using runaway transport techniques for determining internal magnetic fluctuations. A profile of the magnetic fluctuation level in the HL-1M can be estimated from Dr.