The statistical properties of the repeating fast radio burst FRB 121102 are investigated .
We find that the cumulative distributions of fluence , flux density , total energy and waiting time can be well fitted by the bent power law .
In addition , the probability density functions of fluctuations of fluence , flux density and total energy well follow the Tsallis q -Gaussian distribution .
The q values keep steady around q \sim 2 for different scale intervals , indicating a scale-invariant structure of the bursts .
The statistical properties of FRB 121102 are very similar to that of the soft gamma repeater SGR J1550-5418 .
The underlying physical implications need to be further investigated .