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Our results have shown that most informative parameters of AE diagnostics are amplitude, rise time, width of frequency spectrum of AE signals. We found that the width of frequency spectrum of AE signals varies when elastic waves propagate in a solid due to the substantial attenuation of high-frequency components is greater than 12 dB/m, in the same time for low-frequency components this value lies in the range 2,5...8,0 dB/m. We established that the rise time of AE signals contains the information on mechanisms and dynamics of fracture. Its value lies within the interval 0,05 < tau < 2 micro s for brittle fracture and within the range 2 < tau < 15 micro s for ductile fracture. We developed the criterion for evaluation fracture type, which takes into account a sensitivity and gain-frequency characteristic of AE transducer, mode of operations of analog circuit of the AE measuring system, power and frequency parameters of AE signal. Test results that we obtained for a number of structure materials of different physical structure have shown that the range of criterion parameter Zeta variation could be separated as follows: the case Zeta > 400 corresponds to brittle fracture and the case Zeta . 400 corresponds to ductile fracture. We developed new conception of analog channel design for measuring AE circuit, which allows to record informative parameters of AE signal without essential distortions. Using this channel, we developed the portable multi-channel AE system and conducted its metrological certification. We proposed the guidelines on AE diagnostics of products and structure elements accounting for both the criterion of fracture type evaluation and developed diagnostical AE system.