The thyristor valve group is the core element to assure normal operation of transformer type controllable reactor（CRT）and the study of its structure is also the key of structure design and manufacture of CRT. Firstly

the voltage and current of CRT thyristor valve group are calculated on the basis of equivalent circuit of CRT

the two structure parameters（parallel-connected number of stage and seriesconnected number of stage）describing the structure of CRT thyristor valve group is determined and its influencing factor is analyzed. Based on this

the method that the current of thyristor valve group is taken as the free quantity and assigned the definite value to design the structure of CRT thyristor valve block

is proposed and

at the same time

its design process is provided. Finally

in an example

two structure parameters corresponding to each thyristor valve group are calculated and analyzed under different operation modes by using the design method about thyristor valve block structure proposed in this paper. It is shown by the result that the method taking the current of thyristor valve block as the free quantity and assigning it to the determined value to design the structure of thyristor valve block is reasonable. Under the condition of meeting harmonic requirement

the series-connected number of stage for each thyristor valve block structure is closely related to the operation mode

control winding series and control winding current

while the parallel-connected number of stage is free from above factors and only depends on the magnitude of current of thyristor valve group.