The intensity and complexity of X-ray bursts generally is dependent by horizontal gradients of photospherical magnetic field on the line of polarity inversion. It is documented that lower gradient of H is giving (for weak X-rays) generally gradual drops of fiux, in comparison with higher one. The maxiinal value of X-radiation is proportional to the value of H-gradient on the line of polarity inversion. Generally, this gradient is determining the steepness of the front of the X-burst and of the share of hard X-rays component. This can be explained by difference in the quantity and energy of accelerated electrons in kernels of the flare.